Sheet of nonwoven fabric

ABSTRACT

Provided is a sheet of nonwoven fabric having excellent cleaning performance. The sheet of nonwoven fabric includes a web layer formed by an air-laid method. The sheet of nonwoven fabric includes powder producing alkalinity when in contact with moisture, and has a water-absorbing material as a main component.

TECHNICAL FIELD

The present embodiment relates to a nonwoven fabric sheet, and more particularly, to the nonwoven fabric sheet compounded with material producing alkalinity when in contact with water. The nonwoven fabric sheet of the present embodiment is suitable for cleaning purposes, especially, to be attached to cleaning objects and wiping off the objects during cleaning, and can be preferably used in the field of cleaning equipment or goods.

BACKGROUND ART

Sheets including materials producing alkalinity when wetted with water is known in the related art. For example, PTL 1 discloses a sheet for cleaning with an air-laid nonwoven fabric compounded with alkaline inorganic salt powder, thermobonding fiber and optionally cellulose pulp and exhibiting alkalinity when wetted with water, and a nonwoven fabric including thermofusible fiber as a main component laminated thereon.

CITATION LIST Patent Literature

PTL 1: JP 4671794 B

SUMMARY OF INVENTION Technical Problem

The sheet for cleaning in PTL 1 has a layered structure that requires a nonwoven fabric layer including the thermofusible fiber as a main component. The sheet for cleaning has some stiffness as a whole, it is difficult to wipe off a curved surface or a corner of a cleaning object, and cleaning performance may not be satisfactory.

As the sheet including material producing alkalinity when wetted with water, the sheet does not exhibit desired pH when time passes from wetting with water because of chemical reactions or outflow from the sheet of the material producing alkalinity, or the like. In this case, a desired wiping cleaning effect is not achieved when a user continued using the sheet.

An object of the present invention is to provide a nonwoven fabric sheet having excellent cleaning performance. A further object of the present invention is to provide the nonwoven fabric sheet through which preferred time for use can be easily recognized.

Solution to Problem

The embodiment of the present invention to solve the above described problem includes the following aspects.

1. A nonwoven fabric sheet including a web layer formed by an air-laid method, the nonwoven fabric sheet including powder producing alkalinity when in contact with moisture, wherein the web layer is made of water-absorbing material as a main component.

2. The nonwoven fabric sheet according to 1, wherein the powder is included in the web layer.

3. The nonwoven fabric sheet according to 2, wherein the powder is unevenly distributed on one surface of the web layer in a thickness direction of the web layer.

4. The nonwoven fabric sheet according to 2, wherein the powder is distributed uniformly in a thickness direction of the web layer.

5. The nonwoven fabric sheet according to 1, wherein the powder is laminated in layers in the web layer.

6. The nonwoven fabric sheet according to any one of 1 to 5, wherein the web layer is made of water-absorbing fiber as a main component.

7. The nonwoven fabric sheet according to any one of 1 to 6, wherein the nonwoven fabric sheet includes particulate thermofusible resin with a particle size of 1 μm to 1000 μm.

8. The nonwoven fabric sheet according to any one of 1 to 7, wherein the web layer includes fibrous thermofusible resin with fineness of 1 dtex to 120 dtex and average fiber length of 1 mm to 100 mm.

9. The nonwoven fabric sheet according to any one of 1 to 8, wherein the nonwoven fabric sheet includes a water-permeable or water-absorbing sheet adjacent to the web layer.

10. The nonwoven fabric sheet according to 5, wherein he nonwoven fabric sheet includes a water-permeable or water-absorbing sheet in contact with the powder arranged in layers in contact with the web layer.

11. The nonwoven fabric sheet according to any one of 1 to 9, wherein one surface of the nonwoven fabric sheet is provided with a film layer including films.

12. The nonwoven fabric sheet according to any one of 1 to 11, wherein the nonwoven fabric sheet further includes an acidic layer including powder producing acidity when in contact with moisture.

13. The nonwoven fabric sheet according to any one of 1 to 12, wherein

the nonwoven fabric sheet includes a pH indicator and a carrier in the same layer as a layer of the powder; and

the pH indicator is fixed to the carrier by quaternary ammonium salt.

14. The nonwoven fabric sheet according to 13, further including a binder, wherein the pH indicator is fixed to the carrier by the quaternary ammonium salt and the binder.

15. The nonwoven fabric sheet according to 13 or 14, wherein the same layer includes fiber, and the carrier which the pH indicator is fixed to and the powder are held in a void formed by the fiber.

16. The nonwoven fabric sheet according to any one of 13 to 15, wherein the same layer includes thermofusible resin, and a part of the carrier which the pH indicator is fixed to is fixed by being coated with the thermofusible resin.

17. The nonwoven fabric sheet according to any one of 13 to 16, wherein an adjacent layer adjacent to the same layer includes thermofusible resin, and a part of the carrier which the pH indicator is fixed to in the same layer is fixed by being coated with the thermofusible resin.

18. The nonwoven fabric sheet according to any one of 13 to 17, wherein the quaternary ammonium salt is at least one kind selected from a group including benzalkonium chloride, cetylpyridinium chloride, benzethonium chloride, and didecyldimethylammonium chloride.

19. The nonwoven fabric sheet according to any one of 13 to 18, wherein the carrier which the pH indicator is fixed to is cellulose and/or cellulose derivative.

20. The nonwoven fabric sheet according to any one of 14 to 19, wherein the binder is a water-insoluble macromolecule.

21. A method of manufacturing the nonwoven fabric sheet according to any one of 13 to 20, the method including the steps of:

dissolving the pH indicator and the quaternary ammonium salt in a non-aqueous organic solvent; and

adding solution obtained from the previous step to the carrier.

22. The method of manufacturing according to 21, further including the step of:

forming the carrier into a sheet, wherein

the step of adding is performed before the step of forming a sheet.

23. The method of manufacturing according to 21, further including the step of:

forming the carrier into a sheet, wherein

the step of adding is performed after the step of forming a sheet.

Advantageous Effects of Invention

The nonwoven fabric sheet including powder producing alkalinity when in contact with moisture according to an aspect of the present invention is a nonwoven fabric sheet including the web layer formed by an air-laid method, and the web layer is made of water-absorbing material as a main component. Because, in the nonwoven fabric sheet according to the aspect of the present invention, the web layer is made of water-absorbing material as a main component, it is easily transformed along a cleaning surface of a cleaning object and sticks on the cleaning surface when wetted with water, and therefore, it achieves excellent cleaning performance.

The nonwoven fabric sheet including the powder producing alkalinity when in contact with moisture (hereinafter, also referred to as “alkalinity powder”) according to another aspect of the present invention further includes a pH indicator fixed to a carrier. When the nonwoven fabric sheet is wetted with water, the alkalinity powder is in contact with the water and exhibits alkalinity. Then, the pH indicator colorates (develops color) or changes color depending on the change of the hydrogen-ion concentration, and thereby, changes the color of the nonwoven fabric sheet. A user can recognize that the nonwoven fabric sheet is exhibiting a desired pH, or thereafter, the nonwoven fabric sheet turned not exhibiting the desired pH by the color variation of the nonwoven fabric sheet through visual perception. Therefore, the user can use the nonwoven fabric sheet while the nonwoven fabric sheet is exhibiting the desired pH (that is, during the time when it is suitable for use), and can easily determine the finish time for use of the nonwoven fabric sheet.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A to 1K are diagrams illustrating examples of a configuration of nonwoven fabric sheet according to first and third aspects of the present invention.

FIGS. 2A and 2B (FIGS. 1A and 1B) are diagrams illustrating examples of a configuration of nonwoven fabric sheet according to second and third aspects of the present invention.

FIGS. 3A to 3F (FIGS. 1A to 1F) are diagrams illustrating examples of a configuration of nonwoven fabric sheet according to specific aspects of the present invention.

FIG. 4 is a schematic view illustrating a web-forming apparatus available in a method of manufacturing a nonwoven fabric sheet in embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS Nonwoven Fabric Sheet

A nonwoven fabric sheet according to embodiment of the present invention is a nonwoven fabric sheet including a web layer formed by an air-laid method, the nonwoven fabric sheet including powder producing alkalinity when in contact with moisture, and the web layer is made of water-absorbing material as a main component. In the embodiment of the present invention, the web layer of the nonwoven fabric sheet includes water-absorbing material having quantity of greater than 50 mass %, preferably greater than 60 mass %, more preferably 65 mass % or greater, even more preferably 70 mass % or greater, on the basis of mass of the whole web layer. The nonwoven fabric sheet may include a thermofusible resin.

The nonwoven fabric sheet according to the embodiment of the present invention further includes a pH indicator and a carrier in the same layer as that of the powder, and the pH indicator is fixed to the carrier by quaternary ammonium salt.

The present embodiment is described below with reference to the drawings, but the present embodiment is not limited to the embodiment. In the diagrams, the same numeral indicates the same component. Redundant descriptions may be omitted for the same component.

First Aspect

FIGS. 1A to 1K are diagrams illustrating a configuration of a nonwoven fabric sheet according to first and third aspects of the present embodiment for illustration only but not limitation. Referring now to FIGS. 1A to 1K, the configuration and effect of the nonwoven fabric sheet according to the first aspect of the present embodiment are described.

A nonwoven fabric sheet 1000 according to the first aspect of the present embodiment illustrated in FIG. 1A is made of a single-layered configuration including a web layer 100. The web layer 100 is made of water-absorbing material 110 (not illustrated) as a main component. Powder 120 producing alkalinity when in contact with moisture (not illustrated) is compounded with the web layer 100. The web layer 100 may be formed by the steps of, for example, accumulating web raw materials including the water-absorbing material 110, the powder 120 producing alkalinity when in contact with moisture, and thermofusible resin 130 (not illustrated) into a sheet form by an air-laid method, and heat-melting the thermofusible resin 130 to adhere each component. In the manufacturing process of the nonwoven fabric sheet of the present invention, reactions between the powder 120 producing alkalinity when in contact with moisture and water is prevented by using the air-laid method which is a dry method.

In the web layer 100, the powder 120 producing alkalinity when in contact with moisture is fixed by partially being coated with the thermofusible resin 130. Therefore, the powder 120 producing alkalinity when in contact with moisture hardly drops from nonwoven fabric sheet 1000, and the powder 120 can contact with moisture when the nonwoven fabric sheet 1000 is used.

In this example, the water-absorbing material 110 and the thermofusible resin 130 are compounded together into a fibrous form as constitutive fibers to constitute the web layer 100. However, not limited to this, in the present embodiment, the thermofusible resin may be compounded into a particulate form. Generally, nonwoven fabric sheets have high flexibility and is easy to transform depending on a shape of a cleaning object for cleaning purposes, when thermofusible resin is compounded into a particulate form in comparison with a case that thermofusible resin is compounded into a fibrous form. On the other hand, nonwoven fabric sheets tend to obtain stiffness and be superior in scraping performance for cleaning purposes when thermofusible resin is compounded into a fibrous form. Nonwoven fabric sheets tend to have high flexibility and low stiffness when fewer amount of thermofusible resin is compounded. Therefore, the form and the compounded amount of the thermofusible resin in the nonwoven fabric sheet can be appropriately set depending on target performances. Thermofusible resin in a fibrous form and thermofusible resin in a particulate form may be used together.

In the present embodiment, the powder 120 producing alkalinity when in contact with moisture is included in the nonwoven fabric sheet 1000 itself. Therefore, users of the nonwoven fabric sheet 1000 can save time and effort to compound cleaner or apply the cleaner to dirt.

In the present embodiment, the web layer 100 of the nonwoven fabric sheet 1000 is made of water-absorbing material as a main component. Therefore, when the nonwoven fabric sheet 1000 is wetted with water, the nonwoven fabric sheet 1000 absorbs and retains water, which can prevent outflow of the water and the nonwoven fabric sheet 1000 is relatively flexible. Therefore, the nonwoven fabric sheet 1000 can stick on a cleaning target surface of a cleaning object and can wipe off dirt even if the cleaning target surface (e.g., the surface with the dirt) of the cleaning object is a corner or a curved surface. In this way, components producing alkalinity can be applied to the cleaning object effectively, to float the dirt and make the dirt easy to be removed.

The nonwoven fabric sheet 1010, 1020 illustrated in FIG. 1B and FIG. 1C have multilayered configuration including the web layer 100, and the web layer 100 is made of the water-absorbing material 110 as a main component. In this example, water-permeable or water-absorbing sheet 300 which is a sheet having moisture-passing property (permeability) and/or moisture-absorbing property (absorbency) is provided covering one side or the both sides of the web layer 100. When the nonwoven fabric sheet includes a plurality of water-permeable or water-absorbing sheets 300, these do not need to be the same materials. Hereinafter, the water-permeable or water-absorbing sheet is also simply referred to as water-absorbing sheet. In this example, the web layer 100 and the water-absorbing sheet 300 are next to each other and joined entirely by thermal adhesion by the thermofusible resin in a case that each layer includes thermofusible resin and/or binder added separately between layers. In the present embodiment, the joining may be performed by means such as physical entangling of constitutive fibers of each layer. The web layer 100 and the water-absorbing sheet 300 may be joined not entirely but partially.

According to the configurations of FIG. 1B and FIG. 1C, similar results are obtained with the nonwoven fabric sheet of the configuration illustrated in FIG. 1A.

That is, in the present embodiment, the powder 120 producing alkalinity when in contact with moisture is included in the nonwoven fabric sheet itself. Therefore, users of the nonwoven fabric sheet can save time and effort to compound cleaner or apply the cleaner to dirt.

In the present embodiment, the web layer 100 of the nonwoven fabric sheet is made of water-absorbing material as a main component. Therefore, when the nonwoven fabric sheet is wetted with water, the nonwoven fabric sheet absorbs and retains water, which can prevent outflow of the water. The nonwoven fabric sheet is relatively flexible. Therefore, the nonwoven fabric sheet can stick on a cleaning target surface of a cleaning object and can wipe off dirt even if the cleaning target surface (e.g., the surface with the dirt) of the cleaning object is a corner or a curved surface. In this way, components producing alkalinity can be applied to the cleaning object effectively, float the dirt, and make the dirt easy to be removed.

Note that the configurations of FIG. 1B and FIG. 1C include the water-permeable or water-absorbing sheet 300 in addition to the web layer 100. Therefore, the flexibility of the nonwoven fabric sheet is influenced by the property of the water-permeable or water-absorbing sheet 300 and the ratio that the water-permeable or water-absorbing sheet 300 occupies in the nonwoven fabric sheet. In a case of high flexibility of the water-permeable or water-absorbing sheet 300 itself, the nonwoven fabric sheet including this sheet tends to have high aptitude for the purposes to stick along the cleaning target surface. In a case of high stiffness of the water-permeable or water-absorbing sheet 300 itself, the nonwoven fabric sheet including this sheet tends to have high aptitude for the purposes to scrape the dirt during cleaning. The influence of the property of the water-permeable or water-absorbing sheet 300 increases as the ratio that the water-permeable or water-absorbing sheet 300 occupies in the nonwoven fabric sheet increases.

Furthermore, according to the configurations of FIG. 1B and FIG. 1C, the possibility of the powder 120 producing alkalinity when in contact with moisture dropping from the nonwoven fabric sheet can be further reduced in addition to the above described effects.

The nonwoven fabric sheet 1030, 1040 illustrated in FIG. 1D and FIG. 1E illustrates configurations in which one water-permeable or water-absorbing sheet 300 in the configurations illustrated in FIG. 1B and FIG. 1C is replaced with a film 400 having relatively low air permeability. Each web layer 100 of the nonwoven fabric sheet 1030, 1040 is made of water-absorbing material 110 as a main component. In the configuration with a layer of the film 400 having low air permeability on one side, such effects can be obtained that outflow of water or evaporation of the water including alkaline components generated in use from the surface of the film side is prevented in addition to similar effects of the configurations illustrated in FIG. 1B and FIG. 1C. Furthermore, by sticking the film, the nonwoven fabric sheet obtains strength and is easy to be handled.

The nonwoven fabric sheet 1000 according to the first aspect of the present invention is described above with reference to FIGS. 1A to 1E. In the nonwoven fabric sheet 1000, the web layer 100 is made of the water-absorbing material 110 as a main component. In this configuration, the powder 120 producing alkalinity when in contact with moisture may be uniformly distributed in the thickness direction of the layer due to the existence of the water-absorbing material 110 in the web layer 100, or alternatively, be unevenly distributed in one surface of the web layer 100. Furthermore, the water-absorbing material 110 can absorb and retain moisture. Therefore, the alkaline components generated by reactions between the powder 120 and the moisture can be kept in the nonwoven fabric sheet for some time, and excellent cleaning performance is obtained in the use of the nonwoven fabric sheet 1000.

Furthermore, especially in the case that the water-absorbing material 110 in the web layer 100 is fibrous, the powder 120 is easier to be kept in the layer due to the existence of the water-absorbing material 110. The nonwoven fabric sheet 1000 can easily maintain its shape due to the water-absorbing material 110 being included in the web layer 100. Therefore, yield of the powder 120 can be improved at the time of manufacture, storage and use of the nonwoven fabric sheet 1000, and the powder can be prevented from dropping when the nonwoven fabric sheet 1000 undergoes transformation, for example, being folded. Therefore, loss of the powder 120 producing alkalinity when in contact with moisture is prevented, which leads to cost cut. Cost cut can also be attempted depending on selection of the water-absorbing material itself.

The configurations of the nonwoven fabric sheet according to the first aspect of the present invention are described above with reference to FIGS. 1A to 1E. However, these are illustrations only, and configurations other than these and combinations of these configurations are also within the scope of the present invention.

FIG. 1F to FIG. 1K illustrate variations of the nonwoven fabric sheet 1000 according to the first aspect of the present invention for illustration only and not limitation. The nonwoven fabric sheet illustrated in FIG. 1F to FIG. 1K further includes an acidic layer 200 including powder producing acidity when in contact with moisture in addition to the web layer 100 including the powder 120 producing alkalinity when in contact with moisture made of the water-absorbing material 110 as a main component.

The nonwoven fabric sheet of the present invention according to each configuration exhibits alkalinity in use when moistening a surface of the web layer 100 side of both sides of the nonwoven fabric sheet with water, to make the powder 120 producing alkalinity when in contact with moisture included in the web layer 100 contact with moisture. The nonwoven fabric sheet exhibits acidity in use when moistening a surface of the acidic layer 200 side of both sides of the nonwoven fabric sheet with water, to make the powder producing acidity when in contact with moisture included in the acidic layer 200 contact with moisture.

Generally, oil dirt, dirt from hands, scale of hot water, smell of garbage, scorching of fish grill and the like are known as acidic dirt. Scale of cold water, rust, soap scum, dirt in an electric pot, urinary stone, smell of cigarette, nicotine of cigarette and the like are known as alkaline dirt. It is also known that cleaning effects are high when acidic dirt is neutralized with alkalinity, and alkaline dirt neutralized with acidity.

Excellent cleaning performance is obtained to both acidic dirt and alkaline dirt by using the surface of the web layer 100 side of the nonwoven fabric sheet to the acidic dirt and the surface of the acidic layer 200 side of the nonwoven fabric sheet to the alkaline dirt selectively.

In such way of using, it is preferable that self-neutralizing reactions in the nonwoven fabric sheet during the use, in other words, the reactions between alkaline components in the web layer 100 and acidic components in the acidic layer 200 hardly occur. Therefore, configurations that film thickness of the web layer 100 and the acidic layer 200 is thick, or configurations including another layer between the web layer 100 and the acidic layer 200 like FIG. 1G FIG. 1H, and FIG. 1J are preferable. Self-neutralizing reactions can be reduced by adding water so that only a little water contacts with only one side of the nonwoven fabric sheet in use.

Alternatively, another way of using includes a method using self-neutralizing reactions in the nonwoven fabric sheet during the use. Specifically, using carbonate and/or bicarbonate as the powder 120 producing alkalinity when in contact with moisture, the effect to float dirt increases when applied to a cleaning object because carbonic acid gas is generated through both components of the web layer 100 and the acidic layer 200 reacting when the nonwoven fabric sheet is wetted with water in use.

Second Aspect

FIGS. 2A and 2B are diagrams illustrating configurations of a nonwoven fabric sheet 2000 according to second and third aspect of the present embodiment for illustration only but not limitation. Referring now to FIGS. 2A and 2B, the configurations and effects of the nonwoven fabric sheet according to the second aspect of the present embodiment are described.

The nonwoven fabric sheet 2010, 2020 according to the second aspect of the present embodiment illustrated in FIGS. 2A and 2B includes the web layer 100 and the powder 120 producing alkalinity when in contact with moisture laminated in layers on one surface of the web layer 100. That is, although, in the nonwoven fabric sheet 1000 according to the first aspect, the powder 120 producing alkalinity when in contact with moisture is included in the web layer 100, in the nonwoven fabric sheet 2000 according to the second aspect, the powder 120 producing alkalinity when in contact with moisture is arranged in contact with the web layer 100. The web layer 100 is made of water-absorbing material 110 as a main component.

The laminated configuration of the web layer 100 and the powder 120 can be formed by the steps of, for example, accumulating web raw materials including the water-absorbing material 110 and the thermofusible resin 130 into a sheet form by an air-laid method to form the web layer, further accumulating mixture of the powder 120 producing alkalinity when in contact with moisture and the particulate thermofusible resin thereon, and heat-melting the thermofusible resin. In the manufacturing process of the nonwoven fabric sheet of the present embodiment, reactions between the powder 120 producing alkalinity when in contact with moisture and water is prevented by using a dry method. A layer of the powder 120 producing alkalinity when in contact with moisture laminated on one side of the web layer 100 is also simply referred to as a particle layer hereinafter.

The nonwoven fabric sheet 2000 of the second aspect also achieves similar effects to the nonwoven fabric sheet 1000 of the first aspect. That is, in the present embodiment, the powder 120 producing alkalinity when in contact with moisture is included in the nonwoven fabric sheet 2000 itself. Therefore, users of the nonwoven fabric sheet 2000 can save time and effort to compound cleaner or apply the cleaner to dirt. In the present embodiment, the web layer 100 of the nonwoven fabric sheet 2000 is made of water-absorbing material as a main component. Therefore, when the nonwoven fabric sheet 2000 is wetted with water, the nonwoven fabric sheet 2000 absorbs and retains water, which can prevent outflow of the water and the nonwoven fabric sheet 2000 is relatively flexible. Therefore, the nonwoven fabric sheet 2000 can stick on a cleaning target surface of a cleaning object and can wipe off dirt even if the cleaning target surface (e.g., the surface with the dirt) of the cleaning object is a corner or a curved surface. In this way, components producing alkalinity can be applied to the cleaning object effectively, float the dirt, and make the dirt easy to be removed.

Furthermore, the nonwoven fabric sheet 2000 of the second aspect can take configuration which further includes the acidic layer 200 including the powder producing acidity when in contact with moisture, in addition to the web layer 100 and the powder 120 producing alkalinity when in contact with moisture laminated in layers on one surface of the web layer 100.

The nonwoven fabric sheet of the present embodiment according to the configuration of this variation can achieve excellent cleaning performance to both acidic dirt and alkaline dirt by using the surface of the web layer 100 side of the nonwoven fabric sheet to the acidic dirt and the surface of the acidic layer 200 side of the nonwoven fabric sheet to the alkaline dirt selectively. In this way of using, it is preferable that self-neutralizing reactions in the nonwoven fabric sheet during the use, in other words, the reaction between alkaline components and the acidity components does not occur. To prevent such a reaction from occurring, it is preferable that the acidic layer 200 is provided on a surface opposite to the surface where the powder 120 producing alkalinity when in contact with moisture is laminated in both sides of the web layer 100.

Alternatively, another way of using includes a method using self-neutralizing reactions in the nonwoven fabric sheet during the use. Specifically, using carbonate and/or bicarbonate as the powder 120 producing alkalinity when in contact with moisture, the effect to float dirt increases when applied to a cleaning object because carbonic acid gas is generated through both alkaline and acidic components reacting when the nonwoven fabric sheet is wetted with water in use.

Third Aspect

With reference to FIGS. 1A to 2B again, configuration of the nonwoven fabric sheet (nonwoven fabric) of the third aspect of the present embodiment will be described. In the diagrams, the same numeral indicates the same component. Redundant descriptions may be omitted for the same component.

The nonwoven fabric sheet according to the third aspect has a configuration which further includes a pH indicator and a carrier, compared with the configurations of the first aspect and the second aspect described with reference to FIGS. 1A to 2B. The pH indicator and the carrier are contained in the same layer as a layer (alkaline powder containing layer) including powder 120 producing alkalinity when in contact with moisture (alkaline powder).

In the configuration examples illustrated in FIGS. 1A to 1K, as mentioned above, because the powder 120 producing alkalinity when in contact with moisture (not illustrated) is included in the web layer 100, the web layer 100 is the alkaline powder containing layer. In the configuration examples illustrated in FIG. 2A and FIG. 2B, because the powder 120 producing alkalinity when in contact with moisture is included in the particle layer that contacts with the web layer 100, this particle layer is the alkaline powder containing layer. The alkaline powder containing layer includes the powder 120 producing alkalinity when in contact with moisture, the pH indicator and the carrier. The pH indicator is compounded in a form fixed to the carrier.

In the present description below, when description is given of the configuration where “the pH indicator is included in the nonwoven fabric sheet,” the configuration intends to a configuration where “the carrier includes the pH indicator in a fixed form” unless otherwise noted. When it is described that “the carrier includes the pH indicator in a fixed form,” the pH indicator compounded in the nonwoven fabric sheet does not need to be fixed to the carrier as a whole although the whole volume may be fixed to the carrier. That is, the nonwoven fabric sheet may include the pH indicator which is not fixed to the carrier. One kind can be included as the powder producing alkalinity when in contact with moisture and the pH indicator, but without limitation, several kinds can be included in the same layer and/or different layers of the nonwoven fabric sheet.

As illustrated in FIG. 1F to FIG. 1K, in the configuration where the nonwoven fabric sheet includes the acidic layer (hereinafter also referred to as “an acidic powder containing layer”) including the powder producing acidity when in contact with moisture 200, the pH indicator can be also compounded in the acidic powder containing layer. In the acidic powder containing layer, it is also desirable that the pH indicator is compounded in a form fixed to the carrier.

By the pH indicator included in the carrier in a fixed form, it is easy to compound the pH indicator in a desired layer of the nonwoven fabric sheet, and outflow from the nonwoven fabric sheet of the pH indicator at the time of the use is prevented.

As for the nonwoven fabric sheet according to the present embodiment, the pH exhibited by the sheet, especially a status of whether the sheet is exhibiting desired pH is recognized through visual perception by the color variation of the sheet resulted from the pH indicator included in the alkaline powder containing layer (and the pH indicator included in the acidic powder containing layer if included).

The nonwoven fabric sheet can colorate or change color quickly in response to changes in pH when contacted with moisture by the pH indicator being compounded in the same layer as the alkaline powder containing layer (and acidic powder containing layer if included).

For easy recognition of the color variation, the nonwoven fabric sheet according to the embodiment of the present invention has a configuration where the alkaline powder containing layer and/or the acidic powder containing layer (if included) are the outermost layer, or a configuration which can visually recognize the color of the alkaline powder containing layer from the outside through other layers even if the outermost layer is other layers than the alkaline powder containing layer. For example, other layers may have mesh structures and hole structures, thin thickness, semitransparent or transparent materials to see lower layers.

The alkaline powder containing layer and/or the acidic powder containing layer can include fiber, thermofusible resin, booster, and the like in addition to the pH indicator and alkaline powder and/or acidic powder. The fiber, thermofusible resin and booster may be one kind or several kinds.

A specific aspect described below will be described as examples of configuration where the pH indicator, the alkaline powder and/or the acidic powder do not drop from the nonwoven fabric sheet. Hereinafter, the alkaline powder and/or the acidic powder are also referred to as “functional substances” comprehensively. Moreover, the alkaline powder containing layer and/or the acidic powder containing layer are also referred to as “functional substance containing layer” comprehensively.

First Specific Aspect

FIG. 3A is an example where the functional substance containing layer includes fibers F. In a functional substance containing layer 160 including the fibers F, the functional substance D is prevented from dropping by being retained in voids formed by the fibers F, in other words, in voids of the fibrous structure constituted by the fibers F. The pH indicator I can be retained in the nonwoven fabric sheet by being fixed to the fibers F as a carrier. Alternatively, the pH indicator I can be retained in voids of fibrous structures constituted by the fibers F similar to the functional substance D in a fixed form to different materials from the fibers F as a carrier. Alternatively, the pH indicator I may be retained in both. Details of the carrier will be described below.

The functional substance containing layer 160 including the fibers may consist of the pH indicator I, the functional substance D, and the fibers F only. The functional substance containing layer 160 including the fibers may include thermofusible resin, booster, and the like in addition to the pH indicator I, the functional substance D, and the fibers F. The fibers F itself may be the thermofusible resin.

Second Specific Aspect

FIG. 3B is an example where the functional substance containing layer includes thermofusible resin A. The functional substance containing layer 140 including the thermofusible resin is obtained by melting the thermofusible resin A in a mixture including the pH indicator I, the functional substance D, and the thermofusible resin A. In this example, the pH indicator I and the functional substance D in the functional substance containing layer are fixed (also called tied or adhered) in a condition where a part of the pH indicator I and the functional substance D is coated with the thermofusible resin A.

In the functional substance containing layer 140 including the thermofusible resin, the pH indicator I and the functional substance D are prevented from dropping by being adhered in the condition where a part of the pH indicator I and the functional substance D is coated when the molten thermofusible resin A solidifies. The thermofusible resin A is compounded while not coating the whole of the pH indicator I and the functional substance D, the pH indicator I, and the functional substance D include some part which is not coated by the thermofusible resin A, and contact with water at the time of the use of sheet and elution is ensured.

The functional substance containing layer 140 including the thermofusible resin may consist of the pH indicator I, the functional substance D, and the thermofusible resin A only. The functional substance containing layer 140 including the thermofusible resin can include fibers, booster, and the like in addition to the pH indicator I, the functional substance D, and the thermofusible resin A. The thermofusible resin itself may be fibrous.

Third Specific Aspect

FIG. 3C is an example where a layer adjacent to the functional substance containing layer includes thermofusible resin B. A layer 200 including the thermofusible resin B which is adjacent to the functional substance containing layer 150 is obtained by placing the thermofusible resin B on the surface of the functional substance containing layer 150 and melting the thermofusible resin B by heat. In this example, the pH indicator I and the functional substance D in the functional substance containing layer 150 are fixed in a condition where part of the pH indicator I and the functional substance D is coated in the thermofusible resin B. Note that the thermofusible resin A included in the layer 140 and the thermofusible resin B included in the layer 200 may be the same resin or may be different resins.

The functional substance D included in the functional substance containing layer 150 may be prevented from dropping by partially being coated and adhered when the molten thermofusible resin B solidifies in the layer 200 including the thermofusible resin B adjacent to the functional substance containing layer 150. The functional substance D includes some part which is not coated by the thermofusible resin B, and contact with water at the time of the use of sheet and elution is ensured.

The layer 200 including the thermofusible resin B may consist of the thermofusible resin B only. The layer 200 including the thermofusible resin B may include fibers, booster, and the like in addition to the thermofusible resin B. When including these other components, the layer 200 including the thermofusible resin B can be obtained by placing the thermofusible resin B and mixture of these other components on the surface of the functional substance containing layer 150, and melting the thermofusible resin B by heat.

The nonwoven fabric sheet of the example illustrated in FIG. 3C has a three-layered structure, specifically including the layer 200 including the thermofusible resin B, the functional substance containing layer 150 including the pH indicator I and the functional substance D, and the functional substance containing layer 140 including the pH indicator I, the functional substance D and the thermofusible resin A. In this example, the functional substance containing layer 140 may also contribute to the prevention of powder dropping of the pH indicator I and the functional substance included in the functional substance containing layer 150 placed as an interlayer.

Herein, although the functional substance containing layer 150 including the pH indicator I and the functional substance D, and the functional substance containing layer 140 including the thermofusible resin A in addition to the pH indicator I and the functional substance D are illustrated and described as separate layers, configuration where the pH indicator I, the functional substance and the thermofusible resin A which are constituent materials to constitute these two layers integrally form one layer of the functional substance containing layer 140 which is unevenly distributed in a thickness direction is included in this aspect. According to this aspect, especially, in a case that powdered material is unevenly distributed to one surface of the functional substance containing layer 140, powder dropping can be prevented effectively by placing the layer 200 adjacent to the surface.

Although the pH indicator I and the functional substance D are illustrated and described as included in both the layer 150 and the layer 140, the pH indicator I may be included only in either of the layer 150 and the layer 140. From the viewpoint of visibility of the color variation of the nonwoven fabric sheet, it is preferable that the pH indicator I is included in an outer side of the nonwoven fabric sheet.

In this aspect, the layer 200 including the thermofusible resin B may be provided on the both sides of the functional substance containing layer. In other words, for example, configuration (not illustrated) to include the layer 200 including the thermofusible resin B, the functional substance containing layer, and the layer 200 including the thermofusible resin B in this order is within the present aspect.

In this aspect, for the purpose of functional grant to provide, for example, surface reforming and strength (stiffness), the nonwoven fabric sheet may have a multilayer structure (not illustrated) where other layer 350 is laminated on one side or the both sides of the outer surface of the laminated body of the layer 200 including the functional substance containing layer and the thermofusible resin B. In that case, for the other layer 350, configuration which does not disturb viewing of the color variation of the nonwoven fabric sheet is employed.

Fourth Aspect

The nonwoven fabric sheet according to the embodiment of the above-mentioned present invention may be formed by heat-seal processing. As one example, FIG. 3D illustrates a configuration where the other layers 350 including the thermofusible resin are laminated in the both sides of the functional substance containing layer 150, and four sides are heat-sealed. At least one of the other layers 350 has a configuration through which color of the functional substance containing layer 150 can be recognized.

Fifth Aspect

FIG. 3E is an example where an adhesive layer adjacent to the functional substance containing layer 150 is provided. An adhesive layer 500 adjacent to the functional substance containing layer is obtained by placing the adhesive layer on the surface of the functional substance containing layer. Examples of the adhesive layer includes hot melt adhesives or the like, although it is not limited as long as the layer exhibits an adhesion function to prevent powder dropping of the pH indicator I and the functional substance D included in the functional substance containing layer 150.

Specifically, the nonwoven fabric sheet of the example illustrated in FIG. 3E has a configuration where, for example, the adhesive layer 500 including hot melt adhesives such as thermoplastic resin is intervened between the functional substance containing layer 150 and the other layers 350 and interlayer-adhered by hot melt processing.

More particularly, the nonwoven fabric sheet of the example illustrated in FIG. 3E has the functional substance containing layer 140 including the pH indicator I and the thermofusible resin A on an opposite surface of the adhesive layer 500 of the functional substance containing layer 150. Similar to the case of the example illustrated in FIG. 3C, also in the nonwoven fabric sheet of the example illustrated in FIG. 3E, the functional substance containing layer 140 including the thermofusible resin A may contribute to the prevention of powder dropping of the pH indicator I and the functional substance included in the functional substance containing layer 150 placed as an interlayer. Herein, although the functional substance containing layer 150, and the functional substance containing layer 140 including the pH indicator I and the thermofusible resin A are illustrated and described as separate layers, a configuration where these two layers are constituted integrally and the pH indicator I, the functional substance and the thermofusible resin A which are constituent materials are unevenly distributed in a thickness direction to thereby form one layer of the functional substance containing layer 140 is included in this aspect. According to this aspect, especially, in a case that powdered material is unevenly distributed to one surface side of the functional substance containing layer 140, powder dropping can be prevented effectively by placing the layer 500 adjacent to the surface.

Although the pH indicator I and the functional substance D are illustrated and described as included in the both layers of the layer 140 which is the outermost layer and the layer 150 which is an inner layer than the layer 140, the pH indicator I may be included only in either of these layers. From the viewpoint of visibility of the color variation of the nonwoven fabric sheet, it is preferable that the pH indicator I is included in an outer side of the nonwoven fabric sheet.

Sixth Aspect

The above-mentioned functional substance containing sheet according to the embodiment of the present invention may be formed by embossing. As one example, FIG. 3F illustrates configuration where the other layers 350 are laminated on the both sides of the functional substance containing layer 140 including the thermofusible resin A, and interlayer-adhered by embossing. At least one of the other layers 350 has a configuration through which color of the functional substance containing layer 140 can be recognized.

The configurations of the nonwoven fabric sheet of the present invention are described above with reference to FIGS. 3A to 3F. However, these are illustrations only, and configurations other than these and combinations of, for example, illustrated aspects are also within the scope of the present invention. For example, the layer illustrated as the functional substance containing layer 150 in the diagrams may be the functional substance containing layer 160 including the fibers F or the functional substance containing layer 140 including the thermofusible resin A, or, may be a layer including both the fibers F and the thermofusible resin A. Similarly, configurations which rearrange layers in these layers are within the scope of the present invention.

Each constituent and component of the nonwoven fabric sheet of the present embodiment will be described in detail below.

Web Layer

The nonwoven fabric sheet of the present embodiment includes the web layer formed by an air-laid method. In the present embodiment, the web layer 100 is made of water-absorbing material as a main component, and includes water-absorbing material having quantity of more than 50 mass %, preferably more than 60 mass %, more preferably 65 mass % or greater, even more preferably 70 mass % or greater, on the basis of mass of the whole web layer.

Water-Absorbing Material

The nonwoven fabric sheet of the present embodiment is made of water-absorbing material as a main component. For the water-absorbing material, fibrous water-absorbing material (water-absorbing fiber) can be used such as pulp, hemp, cotton, silk, wool, natural fiber including mineral fiber, regenerated fiber including rayon, polylactic acid, and synthetic fibers including nylon. The water-absorbing fiber can be used, for example, in the form of defibrated chopped fiber. The water-absorbing fiber preferably has the average fiber length from 1 to 100 mm, more preferably from 1 to 60 mm, and further preferably from 2 to 30 mm. The water-absorbing fiber preferably has fineness from 1 dtex to 120 dtex, and more preferably from 1 dtex to 85 dtex. When the average fiber length and the fineness of the water-absorbing fiber are within the ranges, the formation of the web layer is easy and a uniform dispersed state is easy to obtain. Two or more kinds of the water-absorbing material may be used together. For the water-absorbing material, particulate water-absorbing material (water-absorbing resin particle) such as water-absorbing resin particles can be used as an auxiliary agent. Examples of the water-absorbing resin particle include carboxymethyl cellulose, polyvinyl alcohol or superabsorbent polymer (SAP), and the like. The particulate water-absorbing material preferably has the average particle size from 1 to 1000 μm, and more preferably from 10 to 800 μm. When the average particle size of the particulate water-absorbing material is within the range, it is easy to obtain a uniform dispersed state.

The web layer of the nonwoven fabric sheet of the present embodiment is made of water-absorbing material as a main component and preferably is made of water-absorbing fiber as a main component. The powder producing alkalinity when in contact with moisture may disperse in the web layer or be unevenly distributed due to the existence of the water-absorbing material.

When contacted with water and powdery components (alkaline components) dissolved in the water, the water-absorbing material of the present embodiment can absorb and retain the water, and release the water at the time of use of the nonwoven fabric sheet. Therefore, at use of the nonwoven fabric sheet, the alkaline components generated the reaction with water can be applied persistently for some long time to a cleaning target surface of a cleaning object.

Powder Producing Alkalinity When in Contact with Moisture

The nonwoven fabric sheet of the present embodiment includes powder producing alkalinity when in contact with moisture. For the powder producing alkalinity when in contact with moisture, alkaline inorganic salt such as carbonate or bicarbonate can be used. For the alkaline inorganic salt, one from a grade used in cosmetics can be used without particular limitation, and no particular grades are prescribed if it does not touch the human body and cause any problems to the environment. For example, sodium carbonate, sodium hydrogen carbonate, sesquisodium carbonate, potassium carbonate, potassium hydrogen carbonate, calcium carbonate, magnesium carbonate, magnesium bicarbonate, calcium hydrogencarbonate or derivatives thereof, or the like can be used. Two or more kinds of the carbonate and/or bicarbonate may be used together. Particularly, one or both of sodium hydrogen carbonate and sodium carbonate can be preferably used. The alkali inorganic salt is a solid composition, and, for example, is preferably in the form of particle. The alkali inorganic salt may be, for example, in the form carried by a carrier such as silica. The alkali inorganic salt may include water as crystal water. Solubility to water rises when it includes crystal water, and reactivity improves. However, from the viewpoint of preservation steadiness, it is preferable that the layer including the powder producing alkalinity when in contact with moisture does not include moisture which can cause the change in quality by triggering hydrolysis or reactions with acid or the like. For the powder producing alkalinity when in contact with moisture, metal oxide or metal hydroxide such as calcium hydroxide or sodium hydroxide, phosphate or silicate, or the like can be used as well. For the powder producing alkalinity when in contact with moisture used in the present embodiment, particles having average particle diameter from 5 to 5000 μm are preferable. In a case where the average particle diameter is from 5 to 5000 μm, there is little falling off of the particles, excellent usability is obtained by moderate granularity.

In the nonwoven fabric sheet according to the first aspect of the present embodiment, the powder 120 producing alkalinity when in contact with moisture is compounded in the web layer 100. In the nonwoven fabric sheet according to the second aspect of the present invention, the powder 120 producing alkalinity when in contact with moisture is arranged next to the web layer 100. In the present embodiment, the powder producing alkalinity when in contact with moisture can be compounded in the web layer and be arranged in contact with the web layer. A layer of the powder 120 producing alkalinity when in contact with moisture arranged in contact with the web layer 100 is also simply referred to as a particle layer hereinafter.

In the nonwoven fabric sheet according to the first embodiment, the web layer may further include the thermofusible resin in addition to particles of the water-absorbing material and the powder 120 producing alkalinity when in contact with moisture. In this case, particles of the powder producing alkalinity when in contact with moisture and the water-absorbing material can be fixed in the web layer in a condition where part of the particles and the water-absorbing material is coated with the thermofusible resin. Such web layer can be formed by accumulating a mixture including the water-absorbing material, particles of the powder producing alkalinity when in contact with moisture, and the thermofusible resin, for example, on a carrier sheet of the web-forming apparatus, or on the surface of other layers (e.g., water-permeable or water-absorbing sheet) constituting the nonwoven fabric sheet, heat-melting the thermofusible resin to join components.

Particle Layer

In the nonwoven fabric sheet according to the second aspect of the present embodiment, the powder 120 producing alkalinity when in contact with moisture can constitute a particle layer arranged in contact with the web layer 100. The particle layer can further include the thermofusible resin in addition to the particles of the powder 120 producing alkalinity when in contact with moisture. In this case, the particles of the powder producing alkalinity when in contact with moisture is fixed in the condition where part of particles is coated by the thermofusible resin in the particle layer. Such particle layer can be formed by placing a mixture including the particles of the powder producing alkalinity when in contact with moisture and the thermofusible resin on the surface of other layers that constitute the nonwoven fabric sheet, for example, the web layer, and heat-melting the thermofusible resin to adhere the component together.

Thermofusible Resin

The nonwoven fabric sheet of the present embodiment can include the thermofusible resin. The thermofusible resin can be compounded in the web layer and/or the particle layer, and in such case, can function as constituent material which joins the components in the layer and provides strength in each layer. The thermofusible resin can serve as the binder that is arranged in the layers constituting the nonwoven fabric sheet and adheres the layers.

For example, the thermofusible resin can fix the powder producing alkalinity when in contact with moisture (and the water-absorbing material if included) in the particle layer (and the web layer) in the state partially coated, by being uniformly mixed with the powder producing alkalinity when in contact with moisture (and the water-absorbing material if included), accumulated in layers as one of the layer constituting the nonwoven fabric sheet, and heat-molten. The thermofusible resin can take any form of particles, fibers, or others. It is desirable that the thermofusible resin is particulate from the viewpoint of uniform mixture with the powder producing alkalinity when in contact with moisture (and the water-absorbing material if included) in the layer formulation step. It is desirable for the thermofusible resin to be fibrous from the viewpoint of joining a plurality of the particles (and/or fibers) of the powder producing alkalinity when in contact with moisture (and the water-absorbing material if included). For example, the thermofusible resin can be in the form of short cut fiber. The thermofusible resin of various kinds of shapes may be used together.

Examples of the thermofusible resin include low density polyethylene (PE) having a melting point of 95° C. to 130° C., high density polyethylene having a melting point of 120° C. to 140° C., polypropylene (PP) including homopolymers or block copolymers having a melting point of 160° C. to 165° C., polypropylene including copolymers having a melting point of 135° C. to 150° C., low melting point polyethylene terephthalate (PET) having a melting point of 110 to 190° C., low melting point polyamide having a melting point of 100 to 130° C., low melting point polylactic acid having a melting point of 110° C. to 150° C., polybutylene succinate having a melting point of 115° C. The thermoplastic resin having a melting point of higher than 110° C. is preferably used in the present embodiment. Two or more kinds of the thermofusible resin may be used together.

In a case that the thermofusible resin is fibrous, the thermofusible fiber preferably has fineness from 1 dtex to 120 dtex, and more preferably from 1 dtex to 85 dtex. The thermofusible fiber preferably has the average fiber length from 1 to 100 mm, more preferably from 1 to 60 mm, and further preferably from 2 to 30 mm. When the fineness and the average fiber length of the thermofusible fiber are within the ranges, the formation of the web layer is easy, and uniform adhesion power and dispersed state are easy to be obtained.

In a case that the thermofusible resin is particulate, the thermofusible particles preferably have the average particle size from 1 to 1000 μm, and more preferably from 10 to 800 μm. The average particle diameter of the thermofusible resin can be appropriately selected as long as it does not completely coat the powder producing alkalinity when in contact with moisture used.

Composite of the Thermofusible Resin

The above-mentioned thermofusible resin may be a composite made of more than two components. Examples of the composite include core sheath fibers which compound resins having different melting points, side-by-side fibers using different resin in a section perpendicular to a longitudinal direction, and core shell particles having a core and a shell. Among them, core sheath fibers are preferably used because different resins can be easily compounded.

For core sheath fibers, core sheath fibers having lower melting point at the sheath than the melting point at the core are preferably used. An example of the core sheath fibers includes PP/PE composition core sheath fibers including a core constituted of polypropylene fibers (melting point of 160° C.) and a sheath constituted of polyethylene (melting point of 130° C.) formed on the circumference of the core.

For example, other core sheath fibers include PET/low melting point PET composition core sheath fibers, high density polyethylene/low density polyethylene composition core sheath fibers, polyethylene/low melting point PET composition core sheath fibers, polyamide/low melting point polyamide composition core sheath fibers, polylactic acid/low melting point polylactic acid composition core sheath fibers, polylactic acid/polybutylene succinate composition core sheath fibers, and the like.

Generally, core sheath fibers have melting points of higher than 110° C. at the sheath, and such core sheath fibers are preferably used in the present embodiment.

In a case that core sheath fibers having lower melting point at the sheath than melting point at the core for the nonwoven fabric sheet of the present embodiment, when heated up to the temperature that is equal to or higher than the melting point of the sheath but lower than the melting point of the core, the resin of the sheath melts, and the resin of the core maintains its shape. In this way, the molten resin at the sheath portion achieves an effect to attach components of the structure constituted of the water-absorbing material and fibers of the core while retaining carbonate and/or bicarbonate in the carbonate layer, and/or retaining acid in the acidic layer. Therefore, the nonwoven fabric sheet of the present embodiment can provide sheet strength and provide a soft sheet excellent in strength while having voids in the sheet.

The composite of two or more components stated above can provide thermal adhesion performance and can function as a binder due to the existence of the thermofusible resin exposed outside. Therefore, these composites can be compounded as the thermofusible resin in the present embodiment.

Acidic Layer

A variation included in the scope of the present embodiment can include configuration which further includes the acidic layer including the powder producing acidity when in contact with moisture. In this case, carbonate and/or bicarbonate are used for the powder producing alkalinity when in contact with moisture compounded in the nonwoven fabric sheet. According to the configuration of this variation, when wetted with water in use, carbonic acid gas is produced by the powder producing acidity when in contact with moisture and carbonate and/or bicarbonate included in separate layers dissolving in water and putting together. The nonwoven fabric sheet of this variation can float dirt by carbonic acid gas, and excellent cleaning performance is obtained when applied to a cleaning target surface of a cleaning object.

For the powder producing acidity when in contact with moisture, acid from the grade used in cosmetics can be used without particular limitation, and no particular grades are prescribed if it does not touch the human body and cause any influences to the environment. For example, malonic acid, maleic acid, citric acid, malic acid, tartaric acid, succinic acid, fumaric acid, hyaluronic acid, sodium dihydrogen phosphate or derivatives thereof, or substances which produce acid when hydrolyzed can be used. Two or more kinds of acid may be used together. The acid is a solid composition, and, for example, is preferably in the form of particle. In the present description below, the powder producing acidity when in contact with moisture is also simply referred to as acid particles. The acid may include water as crystal water. Solubility to water rises when it includes crystal water, and reactivity improves. However, from the viewpoint of preservation steadiness, it is preferable that the acidic layer does not include moisture which can cause the change in quality by triggering hydrolysis or reactions with carbonate and/or bicarbonate or the like. For the acid used in the present embodiment, particles having average particle diameter from 5 to 5000 μm are preferable. In a case where the average particle diameter is from 5 to 5000 μm, there is little falling off of the particles, excellent usability is obtained by moderate granularity. In a case that the average particle diameter is smaller, speed of dissolution is faster and volume of CO₂ gasification of the early period of use increases because the reaction progresses immediately after wetted with water. Granularity can be reduced which can affect the usability of the nonwoven fabric sheet. On the other hand, in a case that the average particle diameter is larger, it is effective in extending a duration of the carbonic acid gas generating because dissolution gradually progresses when wetted with water. It is effective in reducing particle dropping by increasing the average particle diameter.

The acidic layer may further include the thermofusible resin in addition to the acid particles. In this case, the acid particles are fixed in the acidic layer in the conditions where part of the acid particles is coated by the thermofusible resin. Such acidic layer can be formed, for example, by placing a mixture of the acid particles and the thermofusible resin on one surface of the other layers constituting the nonwoven fabric sheet, and heat-melting the thermofusible resin.

The acidic layer may further include the water-absorbing material. The water-absorbing material may have a fibrous form. In this case, the acidic layer can be formed, for example, by an air-laid method.

Booster

One or more boosters can be compounded in the nonwoven fabric sheet of the present embodiment depending on the purposes.

Examples of boosters include oily basis, humectant, touch improver, surfactant, macromolecule, thickening gelling agent, solvent, jet agent, antioxidant, reducing agent, oxidizer, preservative, antibiotics, chelating agent, pH regulator, acid, alkali, powder, inorganic salt, ultraviolet absorber, whitening agent, vitamins and derivatives thereof, antiphlogistic, antiinflammatory, drug for the hair-growth, blood circulation accelerant, spur, hormones, antiwrinkle agent, antiaging agent, tightening agent, cooling agent, calefacient, wound healing accelerant, stimulation palliative, pain-killer, cell activating agent, plant animal microbe extract, antipruritic agent, keratin detachment resolvent, antiperspirant, tonic, convergence agent, enzyme, nucleic acid, fragrance, pigment, coloring agent, dye, pigment, metal containing compound, unsaturated monomer, polyvalent alcohol, high polymer additive, antiphlogistic balm, antifungal drug, antihistamine, hypnosis sedative, tranquilizer, antihypertensive, depression diuretic, antibiotic, anesthetic, antibacterial agent, antiepileptic drug, coronary vessel expansion agent, crude drug, adjuvant, wetting agent, thickener, adhesion grant substance, antipruritic, keratin softening remover, oily raw materials, ultraviolet blocker, prevention of decay sterilizer, antioxidant substance, liquid matrix, fat solubility substance, high polymer carboxylate, additive, metal soap, and the like.

The booster can be compounded in the web layer. In a case that the nonwoven fabric sheet has layers different from the web layer, it can be added to the web layer and one of other layers or both.

Water-Permeable or Water-Absorbing Sheet

For the water-permeable or water-absorbing sheet 300 of the present embodiment, any sheet can be used among sheets having moisture-passing property (permeability) and sheets having moisture-absorbing property (absorbency). There is no limitation for the sheets having moisture-passing property (permeability) as long as it passes water. For the sheets having moisture-absorbing property (absorbency), sheets which can take in moisture and retain the moisture as well as release internal moisture can be used. In other words, the sheets having moisture-absorbing property (absorbency) applicable to the present embodiment is a kind of the sheets having water-passing property (permeability). The water-permeable or water-absorbing sheet 300 has water absorption speed of 60 seconds or less, and more preferably 30 seconds or less, the water absorption speed being measured in accordance with the method for measurement of the sedimentation rate prescribed by JISL1907 standard. Alternatively, the water absorption (permeable) speed measured in accordance with the drip method prescribed by JISL1907 standard is preferably 60 seconds or less, and more preferably 30 seconds or less. As the water-permeable or water-absorbing sheet 300, water-passing speed is high as water absorptivity is low, and in the nonwoven fabric sheet using this sheet, reactions between the powder 120 producing alkalinity when in contact with moisture and the water progresses quickly, and producing water including alkaline components in a short time. The water-permeable or water-absorbing sheet 300 can retain water including the alkaline components for long time as absorbency (retentivity of moisture) is high.

The water-permeable or water-absorbing sheet 300 can be, for example, nonwoven fabric, cloth or other sheets having mesh structures, and for example, special nonwoven fabrics such as CLAF (trade name), and the like. For example, as the water-permeable or water-absorbing sheet having high water retentivity, any sheets having the property to gradually release inside moisture or absorbed moisture for a long time can be used. Depending on kinds of permeability or the water-absorbing sheet 300, the nonwoven fabric sheet laminated with this sheet obtains improved wiping performance effect with improved wet strength which is strength when wetted. For example, for such water-permeable or water-absorbing sheet 300, nonwoven fabrics such as rayon span lace can be preferably used.

By using a thick sheet or a sheet having low density as a water-permeable or water-absorbing sheet used on a surface, wet strength and scraping performance can be provided to the nonwoven fabric sheet. On the other hand, if a thin sheet or a sheet having high water-permeablility and air-permeability is used, an immediate effect of alkaline components is easy to obtain since invasion of moisture from the surface of the nonwoven fabric sheet and outflow of water including the generated alkaline components to the outside are hardly disturbed. The water-permeable or water-absorbing sheet is selected appropriately in accordance with the purposes and objects.

For the purpose of giving a design or improving wiping performance when used as cleaning equipment, surface finishing such as concavity and convexity may be provided on the surface of the water-permeable or water-absorbing sheet as the outer layer of the nonwoven fabric sheet. Several piled sheets of the water-permeable or water-absorbing sheets may be used.

Film

For the film 400, any film can be used having the flexibility to be applied along a cleaning target surface (including a corner and a curved surface) of a cleaning object when using the nonwoven fabric sheet, and having relatively lower air permeability than other layers of the nonwoven fabric sheet, particularly than the water-permeable or water-absorbing sheet 300.

As the film has low air permeability, effects of prevention of outflow of water including alkaline components generated at the time of use of the nonwoven fabric sheet from a surface on the film side and of prevention of evaporation of moisture increase. Therefore, by being applied to the cleaning target surface opposite to the surface of the film side or the like, it can effectively apply water including alkaline components for a long time to the applied part. For example, films having air-permeability measured by “Testing methods for woven and knitted fabrics” prescribed in Japanese Industrial Standards (JIS) L 1096: 2010 of 200 cm³/cm²/s or less are preferably used, and more preferably 150 cm³/cm²/s or less. This air-permeability is air amount to pass through the film per unit area and unit time when applied with predetermined pressure, and air permeability is higher as the value increases. By using films which relatively have lower air permeability than other layers of the nonwoven fabric sheet, particularly, the water-permeable or water-absorbing sheet, directivity for permeance of carbonic acid gas can be obtained.

Examples of films include polyester, polyvinyl alcohol, polyethylene, polypropylene, resin films such as composite films of polyethylene and polypropylene, and the like.

Other Layers

The nonwoven fabric sheet of the present embodiment can include the other layers 350 for the purpose of functionally providing, for example, providing of surface reforming and strength (stiffness) in addition to the web layer 100, and the functional substance containing layer 140, 150, and 160.

For the other layers 350, for example, any sheets can be used having moisture-passing property (permeability) and/or moisture-absorbing property (absorbency) such as nonwoven fabric, cloth, paper, and the like. Moreover, any films can be used. These sheets and films may be the above-mentioned water-permeable or water-absorbing sheet 300 and film 400.

The other layers 350 may include the thermofusible resin. In a case that the other layers 350 include the thermofusible resin, the thermofusible resin included in the other layers 350 may be the same or may be different from the above-mentioned the thermofusible resin A and B, or may be one kind or combination of several kinds thermofusible resin.

When flims having relatively low permeability are used on one surface of the functional substance containing sheet, eluting of functional components from the surface at the time of the use of the sheet can be prevented. In other words, this can promote that components of the functional substance to elute from the other surface. When transparent or semitransparent films are used, color variation of the nonwoven fabric sheet can be recognized easily from the outside.

Surface finishes such as concavity and convexity and the like, or processing such as formation of holes and slits, may be performed on the surfaces of the other layers 350 which is the outer layer of the functional substance containing sheet. For example, for the purposes such as mats for food trays, and the like, films with holes having a large number of holes formed such as surface materials of hygiene materials and films with slits can be preferably used on one of or both surfaces of the functional substance containing sheet. As such a configuration, at the time of the use of the sheet, internal layers in the functional substance containing sheet can suck in drips of food while eluting the functional substance easily by holes and slits.

Heat-Seal Process

Heat-sealing is a method to adhere layers by applying heat using heating means such as heat sealers, and the like. In the embodiment of the present invention, the functional sheet of the multilayer structure can be formed by, for example, placing the layers 200 including the thermofusible resin as the other layers 350 on the both sides of the functional substance containing layer only including the pH indicator and the functional substance as the interlayer, and heat-sealing the four sides. At least one of layers 200 arranged on the both sides of the functional substance containing layer has a configuration through which users can recognize the color variation of the functional substance containing layer. For example, the layers 200 may be transparent or may be semitransparent, and may be a mesh structure having mesh size which does not allow constituent materials of the functional substance containing layer to leak out to the outside.

Adhesive Layer

The formation method of the adhesive layer is not particularly limited, but it is preferable to be the adhesive layer obtained by hot melt processing. The hot melt processing is a processing method to adhere one sheet and another sheet together by dissolving and extruding thermoplastic resin. It can be used for interlayer adhesion when joining the other layers to the functional substance containing layer.

Examples of thermoplastic resins which can be used for hot melt processing include ethylene vinyl acetate copolymer (EVA), and the like, and resins generally known as hot melt adhesives.

Embossing

Embossing is processing to apply heat by strongly pressing with a die having bumps. This method can be also used for the interlayer adhesion in the multilayer structure. Moreover, this method can be used to perform surface finishing such as concavity and convexity on the functional substance containing sheet having monolayer or multilayer structure.

pH Indicator

The pH indicator is also referred to as acid-base indicator, and is not particularly limited as long as it is an indicator that changes its colors according to hydrogen-ion concentration in response to hydrogen ions in solution.

Examples of the pH indicators applicable to the embodiment of the present invention include synthetic pigment such as methyl violet, thymol blue, congo red, methyl yellow, bromothymol blue (also referred to as brom thymol blue), methyl red, methyl orange, litmus, bromocresol purple (also referred to as brom cresol purple), phenol red, phenolphthalein, cresol phthalein, thymol phthalein, alizarin yellow R, aerio chrome black T, and the like. Natural pigments can be used such as red cabbage pigment, perilla pigment, purple potato pigment, red radish pigment, purple corn pigment, elderberry pigment, and grape/blueberry pigment.

These synthetic pigments and natural pigments are known generally and products can be purchased from manufacturers. Herein, the pH indicator is also simply referred to as a pigment.

Although may be only one kind of the pH indicator is used, using combinations of two or more kinds can provide nonwoven fabric products corresponding to a wide range of changes in pH. For example, it can change color tone in the range of pH 2 to 9 by combining bromothymol blue with methyl orange.

Carrier

A carrier is a substance laying the foundation to fix the pH indicator to the nonwoven fabric sheet. The carrier is also referred to as a carrying body or a support. The carrier is a constituent of the layer where the pH indicator is compounded in the nonwoven fabric sheet. For example, in a case that the nonwoven fabric sheet is a structure including fibers, the pH indicator may be fixed to the nonwoven fabric sheet having the fibers as the carrier. Alternatively, the pH indicator may be fixed to the nonwoven fabric sheet by having components other than the fibers, e.g., particulate matters as the carrier which is retained in the voids of the fibrous structures constituted of the fibers. Alternatively, both cases can be applied.

Examples of the carrier applicable to the embodiment of the present invention include pulp made of wood, hemp, cotton, manila fiber, and the like, cellulose substances such as cellulose, hemicellulose, microcrystals cellulose, ion exchange cellulose, synthetic fibers such as nylon, polyester, acrylic, fine powder of clay minerals such as kaolin, synthetic silica, glass, the silicic acid aluminum, zeolite, bentonite, and the like, starch, and protein. The shape of the carrier is not particularly limited, but may be particulate or may be fibrous.

The pulp is an aggregate of the cellulosic fibers which are withdrawn from wood or other plants mechanically or by chemical treatment. Plants, particularly cell walls generally include cellulose and hemicellulose as a component as water-insoluble polysaccharides. Among them, the cellulose is a polysaccharide (carbohydrates) represented as the molecular formula (C₆H₁₀O₅)_(n), and the hemicellulose is the general term of polysaccharides of the non-cellulose. The pulp is composed primarily of cellulose, and generally includes both cellulose and hemicellulose, but it may include only cellulose. In the present description below, cellulose and hemicellulose may be collectively referred to as cellulose. In other words, for example, in the present specification, the cellulosic fiber is composed primarily of cellulose, and may include only cellulose, or may include cellulose and hemicellulose.

The pulp may be wood pulp obtained from the wood raw materials such as conifers, broadleaf trees, or may be non-wood pulp from non-wood raw materials such as herbage including cotton, hemp. For example, the wood pulp can be obtained by processes such as craft digestion to wood chips, but the manufacturing method is not limited to this, and the wood pulp which is prepared by known methods is included in the examples of the carriers applicable to the embodiment of the present invention.

The microcrystals cellulose is obtained by hydrolyzing pulp, and removing amorphous region, and the main component is crystalline cellulose.

The ion exchange cellulose is cellulose provided with a property as ion-exchanger by introducing the basis to charge cellulose positively or negatively. Examples of the ion exchange cellulose include diethylamino ethyl cellulose, carboxymethylcellulose (CMC), phosphocellulose, and the like.

The cellulose derivative is high molecular compound that cellulose is partially denatured. The above-mentioned ion exchange cellulose is also a kind of the cellulose derivative. Examples of the cellulose derivative include cellulose acetate, carboxymethylcellulose (CMC), hydroxyethyl cellulose (HEC), hydroxypropyl methylcellulose (HPMC), and the like.

From the point that the texture and the appearance are superior when compounded in nonwoven fabric, cellulosic fibers can be preferably used. The cellulosic fibers may be long fibers, may be short fibers, or may be processed into powder. The cellulosic fibers having around from 0.01 mm to 5 mm in fiber length can be preferably used. For example, the powdery celluloses made by J. RETTENMAIER & SOHNE GmBH have the average fiber length from 18 μm to 2.2 mm, so cellulosic fibers of the suitable fiber length can be used.

Although the powdered cellulosic fibers can be used for a pigment coating process without preprocessing, the sheet cellulosic fibers may be used after cut into sizes suitable for the machine process of the latter steps as preprocessing of the pigment coating process and defibrated.

Quaternary Ammonium Salt

The quaternary ammonium salt is compounded to promote color development of the pH indicator and clears up coloring, and strengthen the adhesion to the carrier of the pH indicator.

The quaternary ammonium salt is salt with a quaternary ammonium cation and other anion. The quaternary ammonium cation is a polyatomic ion with positive charge represented in molecular formula NR4+ (wherein, R is an alkyl group or an aryl group), and is known as an always electrically charged material without being influenced by pH of solution in the solution. It is understood that this quaternary ammonium cation attaches the pH indicator to the carrier by surface-active effect and chemical combination such as ionic bonding.

Examples of the quaternary ammonium salt applicable to the embodiment of the present invention include cetyltrimethylammonium chloride, stearyltrimethylammonium chloride, lauryltrimethylammonium chloride, benzyltrimethylammonium chloride, benzyltriethylammonium chloride, cetylpyridinium chloride, benzalkonium chloride, benzethonium chloride, dialkyldimethylammonium chloride, didecyldimethylammonium chloride, distearyldimethylammonium chloride. Cetylpyridinium chloride, benzethonium chloride or didecyldimethylammonium chloride can be preferably used. Particularly, benzalkonium chloride can be preferably used.

Binder

The binder is used to fix the pH indicator to the carrier. It is desirable for the binder not to adversely affect color reaction of the pH indicator. It is preferable for the binder to be a non-water-soluble high molecular compound.

Examples of the binder applicable to the embodiment of the present invention include nitrocellulose, cellulose acetate, cellulose derivatives such as ethyl cellulose, polyester resin, alkyd resin, polyurethane resin, epoxy resin, acrylate resin, vinyl resin chloride, vinyl chloride copolymer resin, polyvinyl butyral resin, polyvinyl acetate emulsion, acrylic ester copolymer emulsion, vinylidene chloride copolymer emulsion, epoxy resin emulsion, synthetic resins such as synthetic rubber latex, and the like.

When using a binder to fix the pH indicator to the carrier, at first the binder is dissolved in a solvent in addition to the pH indicator and the quaternary ammonium salt, and the pH indicator mixture solution (hereinafter, also referred to as pigment solution) is prepared. Then, this pigment solution is coated over the carrier by a method such as spray coating or dripping methods. In this way, the pH indicator and the quaternary ammonium salt are fixed to the carrier physically.

The binder is mixed as components of the pigment solution, and thus the binder is preferable to have low viscosity and high solubility to the solvent. It is desirable that the viscosity of the binder is 60 mPa·s or less, more preferably 30 mPa·s or less in the solution that the binder is adjusted to have the final concentration of 10 mass % with ethanol/toluene (1/1) (w/w).

Containing Ratio of Each Component

The web layer of the nonwoven fabric sheet of the present embodiment includes water-absorbing material having quantity of greater than 50 mass %, preferably greater than 60 mass %, more preferably 65 mass % or greater, even more preferably 70 mass % or greater, on the basis of mass of the whole web layer.

The nonwoven fabric sheet of the present embodiment includes powder producing alkalinity when in contact with moisture. The powder producing alkalinity when in contact with moisture can be compounded in the web layer and/or in contact with the web layer. The containing ratio (X:Y) of the water-absorbing material (X) in the web layer and the powder (Y) producing alkalinity when in contact with moisture in the nonwoven fabric sheet is, for example, in the range of more than 50%:less than 50% to 90%:10%, preferably greater than 60%:less than 40% to 90%:10% on the mass basis.

The web layer can further include the thermofusible resin (Z). In this case, the containing ratio [X:(Y′+Z)] (mass basis) of the water-absorbing material (X) in the web layer and the total (Y′+Z) of the powder (Y′) producing alkalinity when in contact with moisture and the thermofusible resin (Z) is, for example, in the range of more than 50%:less than 50% to 90%:10%, preferably greater than 60%:less than 40% to 90%:10% on the mass basis.

When the ratio is in the range, the nonwoven fabric sheet can preferably retain moisture at the time of the use and have flexibility, and apply generated alkaline components to a cleaning target surface precisely. The powder producing alkalinity when in contact with moisture can be retained before use in the thickness direction in the web layer and powder dropping can be prevented.

In addition, in a case of including the web layer and layers different from the web layer, one or more boosters can be adequately compounded in one or more layers of the different layers (e.g., the particle layers).

Containing Ratio of Components

The compounded amount of the functional substance (the powder producing alkalinity when in contact with moisture and the powder producing acidity when in contact with moisture if included) in the nonwoven fabric sheet also varies according to the kinds, the purposes and the desired effects of the materials.

For example, from the viewpoint of effect of the desired function exhibition, the compounded amount is preferable to be greater. However, from the viewpoint of effect of the prevention of powder dropping, the compounded amount is preferable to be lower. For example, it is preferable for the compounded amount to have powdery amount of 0.01 mass % or greater for the sheet whole volume, more preferably 0.2 mass % or greater, further preferably 0.5 mass % or greater, and particularly preferably 1 mass % or greater, or preferably 1 mass % or greater, more preferably 3 mass % or greater, further preferably 5 mass % or greater, even more preferably 8 mass % or greater, and particularly preferably 10 mass % or greater. For example, it is preferable for the compounded amount to have powdery amount of 60 mass % or less for the sheet whole volume, more preferably 50 mass % or less, and further preferably 40 mass % or less.

Basis Weight

The basis weight of the nonwoven fabric sheet can be set depending on the purpose appropriately. For example, it is preferable for the basis weight of the nonwoven fabric sheet to be from 30 to 300 g/m². In other words, in a case that the nonwoven fabric sheet is single-layered configuration including the web layer, the basis weight of the web layer itself can be from 30 to 300 g/m². In a case that the nonwoven fabric sheet includes the water-permeable or water-absorbing sheet 300 and/or the film 400, the basis weight of the total with the web layer and the water-permeable or water-absorbing sheet 300 and/or the film 400 constituting in the nonwoven fabric sheet can be from 30 to 300 g/m². The ratio of the basis weight of the web layer and the basis weight of the water-permeable or water-absorbing sheet 300 and/or the film 400 in the nonwoven fabric sheet can be appropriately set depending on purposes and target quality.

Method of Manufacturing the Nonwoven Fabric Sheet

For example, one method of manufacturing of the nonwoven fabric sheet according to the first aspect of the present embodiment illustrated in FIG. 1A includes a method using a web-forming apparatus employing the air-laid method which is generally known. For example, the components can be joined by laminating a uniform mixture of the water-absorbing material, the powder producing alkalinity when in contact with moisture, and for example, the thermofusible resin such as polyethylene (PE) on a carrier sheet to convey the web layer, placing a carrier sheet thereon, and heat-melting the thermofusible resin melt. At this time, the layer configurations illustrated in FIG. 1B or FIG. 1C may be obtained by using the water-permeable or water-absorbing sheet of the present embodiment as one or both of two carrier sheets. The layer configurations illustrated in FIG. 1D or FIG. 1E may be obtained by using any film which has relatively lower air permeability than the other layers as one of the carrier sheets. The carrier sheets are not required in the present embodiment and may be removed from the formed laminated body after the above described heat treatment. In the present embodiment, these laminating is performed by a dry method to prevent reactions between the powder producing alkalinity when in contact with moisture and water at the time of the production. A web-forming apparatus employing the air-laid method known generally can be used for the formation of the web layer having the water-absorbing material as a main component.

One method of manufacturing the nonwoven fabric sheet according to the second aspect of the present embodiment illustrated in FIGS. 2A and 2B, for example, is a method using the manufacturing method of creating the web layer including the water-absorbing material by the web-forming apparatus employing the generally known air-laid method, and laminating the other layers separately thereon. As such a method, the particle layer can be formed by placing a uniform mixture of the powder producing alkalinity when in contact with moisture and adhesive binder particles such as polyethylene (PE) on the surface of the web layer including the water-absorbing material, heat-melting the adhesive binder to join them. At this time, when creating the web layer including the water-absorbing material by the web-forming apparatus employing the air-laid method, the nonwoven fabric sheet having the layer configuration illustrated in FIG. 2A may be obtained by forming a laminated body by using the water-permeable or water-absorbing sheet of the present embodiment as the carrier sheet to convey the web layer. The layer configurations illustrated in FIG. 2B may be obtained by using any film which has relatively lower air permeability than the other layers as one of the carrier sheets. The carrier sheet is not required in the present embodiment and may be removed from the formed laminated body after the above described heat treatment.

The layers of the nonwoven fabric sheet created separately may be joined by embossing and applying heat-seal processing. There are also methods to join the layers by providing an adhesive layer on at least one side of the bonding surface of the layers of the nonwoven fabric sheet. In the present embodiment, these laminating is performed by a dry method to prevent reactions between the powder producing alkalinity when in contact with moisture and water at the time of the production.

Method of Manufacturing the Nonwoven Fabric Sheet Employing the Air-Laid Method

An example of the method of manufacturing the nonwoven fabric sheet of the present embodiment employing the air-laid method is illustrated in greater detail. This method includes steps of defibrating, mixing, web-forming, and attaching.

Defibrating Step

The defibrating step is a step to defibrate a material in the form of short cut fiber by an air stream, and to obtain defibrated short cut fiber.

The defibrating method with the air stream of the short cut fiber forms an air stream by a blower or the like, supplies the short cut fiber to the air stream, and defibrates the short cut fiber by the stirring effect of the air stream.

For a defibrating method, it is preferable to defibrate by a rotating air stream. The defibrating method using the rotating air stream can defibrate the short cut fiber adequately, and increase dispersibility of the defibrated short cut fiber when forming the air-laid web by the air-laid method.

Examples of the defibrating method using the rotating air stream include a method to put the short cut fiber in a blower and defibrate with the blower. Examples of the defibrating method include a method to supply air to flow along the circumference direction in a cylindrical container by a blower to form a rotating flow, supply the short cut fiber in the rotating flow, and stir and defibrate the short cut fiber.

The speed of the air stream is selected depending on an amount of the short cut fiber appropriately, but it is usually within a range from 10 to 150 m/s.

Mixing Step

The mixing step is a step to obtain web raw materials by mixing the water-absorbing material in the form of the defibrated short cut fiber and other required constituent material for the web layer. In the first aspect of the present embodiment, other required constituent material for the web layer includes the powder producing alkalinity when in contact with moisture. At this time, any other materials can be mixed at the same time. The shape of any other materials is fibrous or particulate. Examples of any other materials include thermofusible resin, water-absorbing resin particle, assistants added as needed such as boosters. The order of addition of these materials does not have particular limitation, and these materials can be added, for example, in later steps after the mixing step by dispersion, and the like.

It is preferable to stir the defibrated short cut fiber and other materials to improve dispersibility of the defibrated short cut fiber when mixing. However, it is preferable to apply the stirring using the air stream but not stirring using mechanical shearing force in order to prevent breaks of the defibrated short cut fiber.

The mixing step may be performed after the defibrating step or at the same time. In a case of performing the mixing step and the defibrating step at the same time, the defibrated short cut fiber and any materials are mixed using the air stream in the defibrating step. Any particles may be put into the web-forming line of the defibrated short cut fiber in a particle dispersion step described below and may be mixed.

Web-Forming Process

The web-forming step is a step to obtain the air-laid web from web raw materials by the air-laid method. Here, the air-laid method is a method to accumulate fibers at random three-dimensionally using the air stream, and to form a web.

Particle Dispersion Step

The particle dispersion step is a step to compound powders with web raw materials by a known method. Either a method to mix powders into fibers and form the web, or a method to spray on the surface of the web or the carrier sheet may be used. The powder producing alkalinity when in contact with moisture may be sprayed on the surface of the web or the carrier sheet in this the particle dispersion step.

For example, in the web-forming step in the present embodiment, the web-forming apparatus 1 illustrated in FIG. 4 is used. This web-forming apparatus 1 includes a conveyor 10, an air permeable endless belt 20, a fiber mixture supplyer 30, a first carrier sheet supplyer 40, a second carrier sheet supplyer 50, and a suction box 60.

Here, the conveyor 10 is configured by a plurality of rollers 11. The air permeable endless belt 20 is mounted to conveyor 10 and is configured to rotate. The fiber mixture supplyer 30 is configured to supply a fiber mixture to the air permeable endless belt 20 with an air stream. The first carrier sheet supplyer 40 is configured to supply a first carrier sheet 41 for the air permeable endless belt 20. The second carrier sheet supplyer 50 is configured to supply a second carrier sheet 51 for the first carrier sheet 41 through the air permeable endless belt 20. The suction box 60 is configured to suck up the air permeable endless belt 20 inside.

In the web-forming apparatus 1, the fiber mixture supplyer 30 is installed on the upper part of the air permeable endless belt 20, the first carrier sheet supplyer 40 is installed upstream than the air permeable endless belt 20, and the second carrier sheet supplyer 50 is installed downstream than the air permeable endless belt 20.

In the web-forming step using the above described web-forming apparatus 1, the air permeable endless belt 20 is rotated by rotating the rollers 11 in a same direction to drive the conveyor 10. The first carrier sheet 41 is sent out from the first carrier sheet supplyer 40 to come into contact with the air permeable endless belt 20.

Then, the suction box 60 sucks up the air permeable endless belt 20, and the fiber mixture is dropped from the fiber mixture supplyer 30 with the air stream, and laminated on the first carrier sheet 41 on the air permeable endless belt 20. In this way, an air-laid web W is formed. The air-laid web W formed in this way is the web layer of the nonwoven fabric sheet according to the present embodiment. In a case that the basis weight of the web layer is large, it can retain water including alkaline components for long time.

Subsequently, an air-laid web containing laminating sheet is obtained by supplying the second carrier sheet 51 from the second carrier sheet supplyer 50 on the air-laid web W.

Attaching Step

It is preferable to use a thermal bond method for the attaching method from a viewpoint to attach without using water. The attaching step according to the thermal bond method is a step to heat-treat the air-laid web and attach the defibrated short cut fibers to each other by the thermofusible resin.

The heat treatment of the air-laid web includes a hot wind process, and an infrared irradiation process, and the hot wind process is preferable since the apparatus is low-cost.

Examples of the hot wind process include a method to heat-treat by making the air-laid web contact with a through-air dryer including a rotatable drum having air permeability on the peripheral surface (hot wind circulation rotary drum method) and a method to heat-treat the air-laid web by passing it through a box-type dryer and passing a hot wind to the air-laid web (hot wind circulation conveyor oven method).

In a case that the air-laid web is inserted between the first carrier sheet and the second carrier sheet and forms the laminating sheet like the present embodiment, it may be processed with a hot wind as a laminating sheet. The first carrier sheet and the second carrier sheet can be peeled off after the hot wind process from the air-laid web. The heat treatment temperature may be the temperature that the thermofusible resin melts. For example, it is desirable to set the heating temperature higher than 115° C. in a case that using materials such as PP and PE which are used generally in the thermal bond method.

It may be passed through a heated roll and compressed for the purpose of fine-tuning thickness and density of the nonwoven fabric sheet after the attaching step.

Formation of Functional Substance Containing Layer

A method of manufacturing the nonwoven fabric sheet according to the third aspect of the present embodiment will be described. The nonwoven fabric sheet according to the third aspect includes a layer (the functional substance containing layer) including the powder producing alkalinity when in contact with moisture. In the present embodiment, the functional substance containing layer is a layer provided by the dry method. The dry method that can be used in the present embodiment includes any non-aqueous layer formulation method without water. Moreover, similar methods of manufacturing can be also employed to layers including the powder producing acidity when in contact with moisture, which is any other functional substance containing layers.

Method of Applying Pigment Solution to Carrier

The functional substance containing layer of the nonwoven fabric sheet of the present embodiment includes the pH indicator (also referred to as pigment hereinafter) in the form fixed to the carrier. Therefore, a step to apply a pigment to the carrier is performed. The method of applying the pH indicator mixture solution (pigment solution) to the carrier, which can be used in the embodiment of the present invention will be described.

Methods to apply pigment to the nonwoven fabric sheet generally include following methods from the viewpoint of the applying step of the pigment to the carrier.

Specifically, there is a method to make components (e.g., cellulosic fibers, and the like) constituting the layer that should compound the pH indicator in the nonwoven fabric sheet carry pigment and make a sheet from the components as raw materials. For example, there is a method to obtain cellulosic fibers on which pigment solution is coated on the surface as raw materials for the sheet by adding a pigment mixture solution while stirring cellulosic fibers with a mixer, and the like.

Alternatively, there is a method to apply pigment solution on the surface of the nonwoven fabric sheet after making the nonwoven fabric sheet. For example, there is a method to coat the sheet surface by spraying (misting) pigment solution at the time of formation of the nonwoven fabric sheet. The carrier may be given pigment solution by not coating, but impregnation.

Note that the step of making a sheet of components itself can be performed according to the above-mentioned method of manufacturing the nonwoven fabric sheet described according to the first and second aspect.

Solvent

Examples of applicable solvents to create pigment solution (the pH indicator mixture solution) include non-aqueous solvents (organic solvents) such as aromatic hydrocarbon, aliphatic hydrocarbon, esters, alcohols. Solvents are preferable which are removable by a technique of reduced pressure drying and the like after dissolving agents (the pH indicator, quaternary ammonium salt, and accordingly binders, and the like) which are constituent materials of the pigment solution, adjusting uniform pigment solution, and having coated the pigment solution in the carrier. Particularly, alcohols are preferable, and isopropyl alcohol is more preferable.

Compounded Amount

The compounded amount of the pigment (the pH indicator) varies according to the pigments used, but the amount may be enough to recognize clear color variation at the time of use. For example, the compounded amount of the thymol phthalein is preferably from 0.01 to 0.5% (w/w) and more preferably from 0.02 to 0.1% (w/w) to the weight of the carrier. Note that the carrier as used herein means components (fibers, powders, and the like) of the functional substance containing layer in which the pH indicator is compounded in the nonwoven fabric sheet.

The compounded amount of the binder is preferably 3% (w/w) or less and more preferably 2% (w/w) or less to the weight of the carrier. When compounded more than 3%, water repellency of the carrier carrying the pigment increases, the solution is harder to penetrate, and color development performance tends to be worsened.

The compounded amount of quaternary ammonium is preferably from 0.05 to 5% (w/w) and more preferably from 0.1 to 2% to the weight of the carrier. For example, benzalkonium chloride is available as products from manufacturers in the form of water solutions such as 10% water solution and 50% water solution, but the above described values are compounded amounts of solid as benzalkonium chloride.

The above described compounded amounts can be optimized according to the compounded amount of each agent. For example, in a case that a binder is compounded 2% (w/w) to the weight of the carrier, the compounded amount of benzalkonium chloride is preferably from 0.1 to 0.5% (w/w) to the weight of the carrier. In a case that a binder is not compounded, the compounded amount of benzalkonium chloride is preferably from 0.3 to 2% (w/w) to the weight of the carrier.

In other words, although the configuration which does not compound a binder is also included in the embodiment of the present invention, by compounding a binder, adherence of the pH indicator to the carrier can be reinforced, and the compounded amount of benzalkonium chloride can be reduced.

The compounded amount of the solvent is preferably from 10 to 100% (w/w) and more preferably from 15 to 50% (w/w) to the weight of the carrier. When there are few compounded amounts of the solvent, viscosity of the pigment solution is higher, and the uniform mixture with the carrier is difficult. When there are too much solvents, the processing time of the drying step after having mixed the pigment solution and the carrier is longer, causing the increase in the processing time and the increase in the cost.

Compounded Amount of the Carrier

The carrier which fixes the pH indicator I can be compounded in the functional substance containing layers 140, 150, 160 in any ratio. From the viewpoint of visibility of the color variation of the functional sheet, it is preferable to be able to identify the color variation of the pH indicator I clearly.

Purpose of the Nonwoven Fabric Sheet

Purposes of the nonwoven fabric sheet according to the present embodiment are exemplified below.

Examples of the purposes of the nonwoven fabric sheet include (1) protection, (2) medical care, (3) building and engineering materials, (4) hygiene, (5) wipers, (6) agriculture and gardening, (7) life materials, (8) industrial materials, and (9) experiment materials.

(1) An example of protection includes a protective article. A specific example of the protective article includes a mask.

(2) Examples of medical care include gauze, mask, sheets, antibacterial mat, poultice cloth, fomentation cloth, hyperventilation syndrome therapeutic agent.

(3) Examples of building and engineering materials include leakage isolation sheet, protection materials, and anticorrosive.

(4) Examples of hygiene include diaper, sanitary products, first aid outfit, cleaning articles, a wet towel, a mask, and the like. A specific example of the diaper includes a paper diaper, and the like. Specific examples of the sanitary products include a napkin, a tampon, and the like. Specific examples of first aid outfit include gauze, band aid, cotton swab, and the like. Specific examples of the cleaning outfit include wet tissue, makeup cotton, mother's milk pad, cleaning sheet, sweat absorbent sheet (for face, underarm, neck, foot, and the like), antibacterial sanitization sheet, antivirus sheet, antiallergenic sheet, antibacterial deodorization sheet, and the like. A specific example of the mask includes a disposable three-dimensional mask, and the like.

(5) Examples of the wiper include wiper, wet wiper, oil strainer, copier cleaning materials, and the like.

(6) Examples of agriculture and gardening use include sheets for seedbed, whole covering sheets, protection against frost sheets, anti-weed sheet, gardening planter, and the like. When used for agriculture and gardening, it can be used to create anaerobic environment and for forcing.

(7) Examples of life material include packing material, cleaning outfit, bag, food, life miscellaneous goods, kitchen utensils, sporting goods, beauty materials, and the like. Specific examples of cleaning outfit include wiper, chemical dustcloth, scrubbing brush, and the like. A specific example of bag includes desiccating agent bag, and the like. Specific examples for food use include tea bag, coffee bag, food bag, freshness holding material, food water absorption sheet, carbonate injectant, food additive, and the like. Specific examples of the life miscellaneous goods include bath articles, eye mask, cooling sheet, warming sheet, neck scarf, gloves, deodorization sheet, flavor base material, insect repellent, pet sheet, and the like. Specific examples of the kitchen utensils include a drainer sheet, fire extinguishing cloth, and the like. A specific example of the sporting goods includes relieving fatigue materials, and the like. Examples of beauty materials include face mask, puff, beauty pack, beauty glove, and the like.

(8) Examples of industrial material use include industrial materials, electric materials, battery, product material, OA apparatus, AV apparatus, roll, apparatus material, and the like.

(9) Examples of experiment material use include anaerobic environment formation materials, anesthetic, insect attractant, and the like.

The nonwoven fabric sheet of the present embodiment can be preferably used for, particularly, cleaning sheet, life material sheet, beauty sheet, sheets for medical care and hygiene such as gauze, and the like. The same nonwoven fabric sheet can be used in a wide variety of fields and purposes without being limited to the above described classifications.

EXAMPLES

Hereinafter, the present embodiment will be described more specifically by using the embodiment and comparative examples, but the present embodiment is not limited to the following examples.

Evaluation Test

Nonwoven fabric sheets according to the examples and the comparative examples are manufactured as follows, and performance is evaluated.

Evaluation Item and Test Method I. Water Retentivity

It can be assumed that when a nonwoven fabric sheet is wetted with water, the nonwoven fabric sheet can apply a liquid including alkaline components to a cleaning object for longer time as capability to retain water soaked with (water retentivity) is higher. For example, the water retentivity can be determined by an amount of water which a nonwoven fabric sheet can take into and length of time that the nonwoven fabric sheet can keep the taken water inside when the nonwoven fabric sheet is wetted with water.

Here, the water retentivity was evaluated according to the following processes. At first each of the nonwoven fabric sheet (5 cm in width in height) of the examples and the comparative examples was soaked with water of a predetermined quantity (2 ml), squeezed lightly, and the amount of water which the nonwoven fabric sheet cannot retain and overflows was examined by visual observation. Furthermore, the nonwoven fabric sheet after having squeezed lightly was put on a cleaning target surface (the surface of the tile of the 15 cm in width in height), and left for a predetermined time (one minute). The cleaning target surface was inclined to horizontally during this period, and presence or absence of water (liquid dropping) which overflows and drips from the nonwoven fabric sheet was examined by visual observation.

It was determined to be excellent in water-retentivity as there are few amount of the overflowing water.

Note that although it was examined by visual observation here, as an alternative technique, an amount of water which the nonwoven fabric sheet retains and changes thereof may be examined by measuring weight of the nonwoven fabric sheet at each stage with instruments.

II. Performance about Dirt Removal

It can be assumed that when wiping a cleaning target surface by a nonwoven fabric sheet, the performance of the nonwoven fabric sheet to remove dirts is higher if fewer number of wiping times is required before dirts are off, and the required power to remove dirt is small.

Here, a wiping operation to wipe the cleaning target surface was performed with the nonwoven fabric sheet soaked with water, and states of dirt removal is examined by visual observation. In a case that dirt was not removed, a wiping operation by the force of approximately equivalence to the last time was repeated. By the number of times of the wiping operations before dirt is removed, the performance about the dirt removal was evaluated.

Specifically, assuming oil stain attached to a wall of a kitchen, 1 ml of edible oil was sprayed in a mist form to a surface of the tile of the 15 cm in width in height in advance, left in 23° C., 50% RH with constant temperature and humidity for 24 hours, and solidified. Hereinafter, edible oil solidified in this way is referred to as “oil stain.”

The nonwoven fabric sheet was put on a cleaning target surface and left for predetermined time (one minute) according to the same procedure as the above-mentioned water retentivity test with the surface of the tile to which this oil stain attached as the cleaning target surface. Subsequently, a wiping operation to wipe the surface of the tile on which the nonwoven fabric sheet was put on, was performed with the nonwoven fabric sheet put on the surface. Wiping operations were repeated until the oil stain was removed in ten times at maximum.

The performance about the dirt removal was evaluated high and excellent as smaller number of times of the wiping operation before the stain was removed was required.

III. Attaching Property

One method of use of the nonwoven fabric sheet is a method to perform the wiping operation after the nonwoven fabric sheet soaked with water is left in contact with the cleaning target surface and some time passes. According to this method, liquid including alkaline components can be applied intensively to the part of the cleaning target surface which the nonwoven fabric sheet contacts. According to this, the dirt attached to the cleaning target surface can be floated, and cleaning efficiency is considered high.

The cleaning target surface is not necessarily horizontal nor necessarily a flat-like, but may be in a curved surface form and may include a corner or concavities and convexities. To obtain the above-mentioned effect, attaching property is required where the nonwoven fabric sheet can transform along the shape of the cleaning target surface and can contact with the cleaning target surface, and can keep the state for some time.

Here, as attaching properties, two following points were examined by visual observation.

(1) Whether the nonwoven fabric sheet can remain without sliding from the cleaning target surface or being peeled off at the time when the cleaning target surface (the surface of the tile) is inclined against horizontal in examining of the presence or absence of liquid outflow in the above-mentioned water retentivity evaluation test.

(2) Assuming a sink (drainboard) to be a cleaning object as one example, the nonwoven fabric sheet which was dipped into water quickly was left for a predetermined time (one minute) attached to tightly contact along the shape of the corner part (the cleaning target surface) of the sink. Whether the nonwoven fabric sheet can keep the shape as attached without peeled off from the cleaning target surface at this time.

In both of the above-mentioned (1) and (2), it is desirable for the nonwoven fabric sheet not to peel off from the cleaning target surface, and the attaching property was evaluated excellent as the changes of the relative position of the nonwoven fabric sheet to the cleaning target surface was small.

IV. Coloration: Color Variation, Articulacy of the Color Variation and Pigment Outflow

When a nonwoven fabric sheet which is compounded with the functional substance such as powder producing alkalinity when in contact with water and the pH indicator (pigment) is soaked with water, hydrogen-ion concentration (pH) in the water changes by reactions with the functional substance. The pH indicator (pigment) compounded in the sheet reacts accordingly and colorates or changes color, and the color of the sheet changes. Colors corresponding to pH and the articulacy of the color variation can vary according to kinds or compounded amounts of the pH indicator (pigment), and the like. When the pH indicator (pigment) does not remain in the sheet by adding water and flows out from the sheet, color migration occurs in the water, and the color variation might not be clear since the color of the sheet becomes light.

Here, for an index of the coloration of the sheet, sheet raw materials in the form that the pH indicator (pigment) is fixed to the cellulosic fiber as the carrier was used and examined instead of a sheet. For pH indicators, a plurality of indicators which change in the range of acidity to weak alkali were examined. Specifically, the coloration (color variation, articulacy of the color variation and color outflow) of sheet raw materials were examined by visual observation according to the following processes.

(1) The pigment coating cellulosic fibers 2, 3 obtained from the examples of experiments described below were soaked with each of pH regulators (acidity, neutrality, alkalinity) of 5 times as much as their quantity (mass basis), respectively.

For an acidic pH preparation agent, 0.1N of sulfuric acid (pH 1.4) was used. For a neutral pH regulator, 1M of phosphate buffer (pH 7.0) was used. For an alkaline pH regulator, 0.1% of Ca(OH)₂ (pH 2.0) was used.

(2) The color variation of the cellulosic fibers 2, 3 in response to the pH regulators, articulacy of the color variation and the outflow of the pigment to a liquid were examined by visual observation.

In this way, for each the pH indicator, what kinds of color cellulosic fibers exhibit in response to pH were observed. It is preferable as the color variation is clearer because a user is easy to recognize a pH change at the time of use when applied to a nonwoven sheet. It is also preferable as there are fewer outflows of the pigment because the color variation of the sheet is clearer and is easy to recognize a pH change, and, in addition, there is little influence on environment due to the material outflow. Influence of the presence or absence of combination of the binder to the pigment solution in terms of the outflow of the pigment was examined.

V. Sheet Coloration: Color Variation and Pigment Outflow

The following examinations were performed to the nonwoven fabric sheet of an example (specifically Example 4) including a pH regulator in examples described below.

Identification of Color Variation

A formed sheet was cut into 5 cm*5 cm square size, and soaked with water 5 times as much as the sheet weight. At this time, the color and pH of the sheet was examined at each timing of before soaking with water (dry state), right after, 15 minutes later, and 60 minutes later.

Pigment Outflow

For one index of the pigment outflow, color migration was examined by visual observation when a white plastic sheet was wiped with the sheet which developed color. Here, “color migration” means that a pigment which is color development components of the sheet elutes outside the sheet and moves to the plastic sheet. The pigment outflow is preferable to be low as the degree of the color migration is minor. It is more preferable not to be able to see the color migration.

Example 1 Manufacture of Nonwoven Fabric Sheet

Each defibrated short cut fiber was obtained by defibrating short cut rayon fiber (fineness 3.3 dtex, fiber length 5 mm) and short cut core sheath type thermal adhesive composite fabric (PET/PE composition core sheath fiber, fineness 2.2 dtex, fiber length 5 mm, sheath part melting point 130° C.), by using a turning flow type jet stream defibrating apparatus.

Subsequently, a fiber mixture of rayon/(PET/PE) was obtained by mixing rayon fiber in the form of the defibrated short cut fiber and thermofusible composite fiber in the form of the defibrated short cut fiber with a ratio of 60/40 (mass ratio) uniformly by an air stream.

A particulate mixture of sodium hydrogen carbonate/PE powder was obtained by mixing sodium hydrogen carbonate (average particle size 100 μm) and PE powder (average particle size 400 μm) with a ratio of 80/20 (mass ratio).

Subsequently, the sheet formed by the air-laid web using the fiber mixture was obtained using the web-forming apparatus 1 illustrated in FIG. 4 on the carrier sheet.

Specifically, the first carrier sheet 41 including rayon span race nonwoven fabrics (27 g/m² of basis weight, air-permeability 292 cm³/cm²/s) was sent out by the first carrier sheet supplyer 40 on the air permeable endless belt 20 which is running mounted to the conveyor 10.

PE powder was sprayed to be 5 g/m² on the first carrier sheet 41 while sucking up the air permeable endless belt 20 by the suction box 60, and the above described fiber mixture is dropped from the fiber mixture supplyer 30 with an air stream and was laminated thereon. The fiber mixture was supplied to be 100 g/m² of the basis weight per an air-laid web portion on this occasion.

Subsequently, a particulate mixture of sodium hydrogen carbonate/PE powder was sprayed to be 50 g/m² on the air-laid web and accumulated. An air-laid web containing laminating sheet was obtained by laminating the second carrier sheet including rayon span race nonwoven fabrics (27 g/m² of basis weight, air-permeability 292 cm³/cm²/s) thereon.

The obtained laminating sheet was passed through the box type dryer of the hot wind circulation conveyor oven method, and processed with a hot wind at 140° C., and 209 g/m² of basis weight of the nonwoven fabric sheet was obtained.

Example 2 Manufacture of Nonwoven Fabric Sheet

A defibrated short cut fiber was obtained by defibrating short cut core sheath type thermal adhesive composite fabric (PET/PE composition core sheath fiber, fineness 2.2 dtex, fiber length 5 mm, sheath part melting point 130° C.), by using a turning flow type jet stream defibrating apparatus.

Subsequently, a fiber mixture of pulp/(PET/PE) was obtained by mixing conifer chemical pulp and thermofusible composite fiber in the form of the defibrated short cut fiber with a ratio of 60/40 (mass ratio) uniformly by an air stream.

Subsequently, the sheet formed by the air-laid web using the fiber mixture and sodium hydrogen carbonate (average particle size 100 μm) was obtained using the web-forming apparatus 1 illustrated in FIG. 4 on the carrier sheet.

Specifically, the first carrier sheet 41 including rayon span race nonwoven fabrics (27 g/m² of basis weight, air-permeability 292 cm³/cm²/s) was sent out by the first carrier sheet supplyer 40 on the air permeable endless belt 20 which is running mounted to the conveyor 10.

PE powder was sprayed to be 5 g/m² on the first carrier sheet 41 while sucking up the air permeable endless belt 20 by the suction box 60, and the above described fiber mixture and sodium hydrogen carbonate were dropped from the fiber mixture supplyer 30 with an air stream to be the ratio of 100/15 (mass ratio) while mixing and was laminated thereon. The fiber mixture and sodium hydrogen carbonate were supplied to be 115 g/m² of the basis weight per an air-laid web portion on this occasion.

Subsequently, PE powder was sprayed to be 5 g/m² on the air-laid web and accumulated. An air-laid web containing laminating sheet was obtained by laminating the second carrier sheet including rayon span race nonwoven fabrics (27 g/m² of basis weight, air-permeability 292 cm³/cm²/s) thereon.

The obtained laminating sheet was passed through the box type dryer of the hot wind circulation conveyor oven method, and processed with a hot wind at 140° C., and 179 g/m² of basis weight of the nonwoven fabric sheet was obtained.

Example 3 Manufacture of Nonwoven Fabric Sheet

A sheet was obtained similar to Example 1 except a tissue (14 g/m² of basis weight) made of wood pulp raw materials as the second carrier sheet was laminated instead of a rayon span race nonwoven fabric, and a film (PE, basis weight 26 g/m²) on which 5 g/m² a hot melt adhesive (ethylene, vinyl acetate copolymer) was applied was laminated thereon so that the surface of the side where the hot melt adhesive of the film was applied was faced with the tissue. The basis weight was approximately 227 g/m².

Example 4 Create of Pigment Solution

50 g of bromothymol blue solution (the solvent is ethanol) with the 2% concentration, 10 g of benzalkonium chloride water solution with the 50% concentration, and 40 g of polyvinylbutyral were dissolved in isopropanol, and diluted with isopropanol to 500 g in total (mass/mass basis). The mixture was prepared by mixing until polyvinyl butyral completely dissolved, and the pigment solution C1 was obtained.

Application of Pigment Solution to Carrier

25 g of the pigment solution C1 of was added while stirring 50 g of powdered cellulosic fibers (fiber length 0.2 mm) with a mixer, and stirred until fibers and the pigment solution were mixed uniformly. Subsequently, it was dried with a dryer under conditions of 105° C. for two hours, and the solvent was removed, and the powdered pigment coating cellulosic fiber 1 (fiber length 0.2 mm) was obtained.

Manufacture of Nonwoven Fabric Sheet

A sheet was obtained similarly to Example 1 except that a particulate mixture of sodium hydrogen carbonate/PE powder/pigment coating cellulosic fiber was obtained, by mixing sodium hydrogen carbonate (100 μm in an average particle diameter), PE powder (400 μm in an average particle diameter), pigment coating cellulosic fiber 1 in a ratio 70/25/15 (mass ratio), instead of a particulate mixture of sodium hydrogen carbonate/PE powder. The basis weight was approximately 185 g/m².

Comparative Example 1

A sheet was obtained similar to Example 1 except that PE powder (average particle size 400 μm) is sprayed and accumulated on the air-laid web to be 5 g/m² instead of the particulate mixture. The basis weight was approximately 164 g/m².

Comparative Example 2

The air-laid web containing sheet was obtained similarly to Example 1 except that a core sheath type thermal adhesive composite fiber (PET/PE composition core sheath fiber, fineness 2.2 dtex, fiber length 5 mm, sheath part melting point 130° C.) in the form of the defibrated short cut fiber was used instead of a fiber mixture of rayon/(PET/PE).

Examples of Experiments 1 to 8 Preparation of Pigment Solution

At first, for eight kinds of the pH indicators (pigments) described in following Table 1, 1% solution is prepared. At this time, congo red, indigo carmine, and red cabbage pigment were dissolved in water, and other pigments were dissolved in ethanol to prepare solutions. Then, mixing materials according to the combinations described in table 2, two kinds of the pigment solutions C2, C3 were prepared for each the pH indicator.

TABLE 1 pH Indicator Range of Example of color change experiment pH indicator Abbreviation of pH indicator 1 Thymol blue TB 1.2-2.8/8.0-9.6 2 Methyl red MeR 4.4-6.2 3 Congo red CoR 3.0-5.2 4 Bromothymol blue BTB 6.0-7.6 5 Blomcresol purple BCP 5.2-6.8 6 Cresol phthalein CrP 8.2-9.8 7 Indigo carmine (edible food IdC 11.4-13.0 color) 8 Red cabbage pigment Cab 3.0-5.5-8.0 (natural pigment)

TABLE 2 Combination of Pigment Solution (mass/mass basis) Pigment solution C2 Pigment solution C3 Agent (With binder) (Without binder) pH indicator 0.05% 0.05% Benzalkonium chloride  0.5%  0.5% Polyvinyl butyral   2%   0% Isopropanol diluted to 100 g in diluted to 100 g in total total

Application to Carrier of Pigment Solution

25 g of the pigment solution C2 of was added while stirring 50 g of powdered cellulosic fibers (fiber length 0.2 mm) with a mixer, and stirred until fibers and the pigment solution were mixed uniformly. Subsequently, it was dried with a dryer under conditions of 105° C. for two hours to remove the solvent, and the powdered pigment coating cellulosic fiber 2 (fiber length 0.2 mm) was obtained.

Likewise, except that pigment solution C3 was used in substitution for the pigment solution C2, the powdered pigment coating cellulosic fiber 3 (fiber length 0.2 mm) was obtained.

Test Result

Table 3 indicates the results of the evaluation tests I. to III. Table 4 indicates the result of the evaluation test IV. Table 5 indicates the result of the evaluation test V.

TABLE 3 Results of Evaluation Tests I. to III. I. Water III. Attaching retentivity II. Dirt removal property Example 1 Good Good Good Example 2 Good Good Good Example 3 Good Good Good Example 4 Good Good Good Comparative Example 1 Good Fail Good Comparative Example 2 Fail Acceptable Fail

TABLE 4 Result of Evaluation Test IV. Example Color variation of pigment coating Articulacy Pigment outflow of cellulosic fibers 2, 3 of color Cellulosic Cellulosic experiment Abbreviation Dry state Acidity Neutrality Alkalinity variation fiber 2 fiber 3 1 TB Light Light red Light Blue Good No Yes yellow yellow 2 MeR Light Light Light Light Good No Yes pink pink yellow yellow 3 CoR Light Light Light Light pink Acceptable No No pink purple pink 4 BTB Light Light Light Blue Good No No yellow yellow green 5 BCP Light Light Blue Blue Good No No green yellow 6 CrP Colorless Colorless Colorless Purple Good No Yes 7 IdC Light Light Light Light Fail No No bluish purple bluish purple violet violet 8 Cab Colorless Light Colorless Light Acceptable No No pink yellow

TABLE 5 Result of Evaluation Test V. Example 4 pH Color of sheet Remarks Before wetted with water — Light yellow Dry state Right after wetted with water 8.0 Blue No color migration 15 minutes after wetted with 7.9 Blue No color migration water 60 minutes after wetted with 7.0 Light green No color migration water

The test result is illustrated with signs Good, Acceptable, Fail sequentially from the one that has good evaluation. The specific evaluation details are as follows.

I. Water Retentivity

Good: The nonwoven fabric sheet did not overflow water when squeezed lightly, and was able to retain water soaked with. Liquid outflow was not seen when the nonwoven fabric sheet is put and left on the cleaning target surface.

Fail: The nonwoven fabric sheet refused water, and overflowed water before squeezed lightly, and was not able to retain water soaked with.

II. Dirt Removal

Good: The oil stain was able to be wiped off easily by one wiping operation.

Acceptable: The oil stain was able to be wiped off by performing several times of wiping operations.

Fail: The oil stain was not able to be wiped off even if wiping operations are repeated ten times.

III. Attaching Property

Good: The nonwoven fabric sheet did not peel off from the cleaning target surface.

Fail: The nonwoven fabric sheet peeled off from the cleaning target surface.

IV. Coloration

Good: The color variation was greatly clear.

Acceptable: The color variation was visible.

Fail: The color variation was minor and indistinct.

The nonwoven fabric sheet of the present embodiment was able to retain water including alkaline components adequately as above. The nonwoven fabric sheet of the present embodiment floated oil stain and was able to wipe it off easily. Furthermore, the nonwoven fabric sheet of the present embodiment was not peeled off from the cleaning target surface during the application to the cleaning target surface.

In other words, the nonwoven fabric sheet of the present embodiment may exhibit effects to be able to apply water including alkaline components effectively to the cleaning target surface because the nonwoven fabric sheet is transformed along the shape of the cleaning target surface, and the shape can be maintained while retaining water including alkaline components.

From Examples of Experiments 1 to 8, it is understood that the cellulosic fibers which carry the pH indicator (pigment) change the color in response to a pH change. It is understood that configuration that color variation is produced in desired pH region can be obtained by suitably selecting the pH indicator (pigment) to use. It is understood that clear color variation can be obtained by suitably selecting the pH indicator (pigment) to use. At this time, it is found that the tendency of the pigment outflow for the obtained carrier can be reduced by compounding a binder with a pigment solution to fix the pH indicator (pigment) in the carrier. It can be considered that this is achieved form the pH indicator (pigment) and the carrier being fixed more strongly by the binder.

The nonwoven fabric sheet colorates when the nonwoven fabric sheet is wetted with water in Example 4. A clear change is seen in the color of the nonwoven fabric sheet depending on a change of pH when pH of the water included in the nonwoven fabric sheet changes in timewise.

Therefore, in the nonwoven fabric sheet of the present embodiment, the nonwoven fabric sheet that changes the color in response to the change of pH is obtained by using the carrier carrying the pH indicator (pigment) as a component of the nonwoven fabric sheet. A user can recognize that the nonwoven fabric sheet is exhibiting a pH in a desired pH region, or thereafter, the nonwoven fabric sheet turned not exhibiting the pH in the desired pH region by the color variation of the nonwoven fabric sheet through visual perception. Therefore, the user can use the nonwoven fabric sheet while the nonwoven fabric sheet is exhibiting the pH in the desired pH region (that is, during the time when it is suitable for use), and can easily determine the finish time for use of the nonwoven fabric sheet.

REFERENCE SIGNS LIST

-   1 Web-forming apparatus -   30 Fiber mixture supplyer -   41 First carrier sheet -   51 Second carrier sheet -   100 Web layer -   110 Water-absorbing material -   140 Functional substance containing layer including thermofusible     resin -   150 Functional substance containing layer -   160 Functional substance containing layer including fiber -   200 Acidic layer -   300 Water-permeable or water-absorbing sheet -   350 Other layer -   400 Film -   1000, 2000, 2010, 2020 Nonwoven fabric sheet -   A, B Thermofusible resin -   D Functional substance -   F Fiber -   I pH indicator (pigment) -   W Air-laid web 

1. A nonwoven fabric sheet including a web layer formed by an air-laid method, the nonwoven fabric sheet comprising: powder producing alkalinity when in contact with moisture, wherein the web layer is made of water-absorbing material as a main component.
 2. The nonwoven fabric sheet according to claim 1, wherein the powder is included in the web layer.
 3. The nonwoven fabric sheet according to claim 2, wherein the powder is unevenly distributed on one surface of the web layer in a thickness direction of the web layer.
 4. The nonwoven fabric sheet according to claim 2, wherein the powder is distributed uniformly in a thickness direction of the web layer.
 5. The nonwoven fabric sheet according to claim 1, wherein the powder is laminated in layers in the web layer.
 6. The nonwoven fabric sheet according to claim 1, wherein the web layer is made of water-absorbing fiber as a main component.
 7. The nonwoven fabric sheet according to claim 1, wherein the nonwoven fabric sheet comprises particulate thermofusible resin with a particle size from 1 μm to 1000 μm.
 8. The nonwoven fabric sheet according to claim 1, wherein the web layer comprises fibrous thermofusible resin with fineness of 1 dtex to 120 dtex and average fiber length from 1 mm to 100 mm.
 9. The nonwoven fabric sheet according to claim 1, wherein the nonwoven fabric sheet comprises a water-permeable or water-absorbing sheet adjacent to the web layer.
 10. The nonwoven fabric sheet according to claim 5, wherein the nonwoven fabric sheet comprises a water-permeable or water-absorbing sheet adjacent to the powder arranged in layers in contact with the web layer.
 11. The nonwoven fabric sheet according to claim 1, wherein one surface of the nonwoven fabric sheet is provided with a film layer comprising a film.
 12. The nonwoven fabric sheet according to claim 1, wherein the nonwoven fabric sheet further comprises an acidic layer including powder producing acidity when in contact with moisture.
 13. The nonwoven fabric sheet according to claim 1, wherein the nonwoven fabric sheet comprises a pH indicator and a carrier in the same layer as a layer of the powder; and the pH indicator is fixed to the carrier by quaternary ammonium salt.
 14. The nonwoven fabric sheet according to claim 13, further comprising a binder, wherein the pH indicator is fixed to the carrier by the quaternary ammonium salt and the binder.
 15. The nonwoven fabric sheet according to claim 3, wherein one surface of the nonwoven fabric sheet is provided with a film layer comprising a film.
 16. The nonwoven fabric sheet according to claim 5, wherein one surface of the nonwoven fabric sheet is provided with a film layer comprising a film.
 17. The nonwoven fabric sheet according to claim 3, wherein the nonwoven fabric sheet comprises particulate thermofusible resin with a particle size from 1 μm to 1000 μm
 18. The nonwoven fabric sheet according to claim 3, wherein thermofusible resin is partially coating the powder.
 19. The nonwoven fabric sheet according to claim 7, wherein the particulate thermofusible resin is partially coating the powder. 